Electric  Arc  Welding 


By 


E.  WANAMAKER 

ELECTRICAL     ENGINEER,     CHICAGO,      ROCK.     ISLAND     & 
PACIFIC    RAILROAD 

and 
H.  R.  PENNINGTON 

SUPERVISOR    OF    ELECTRICAL    EQUIPMENT    AND    WELD- 
ING,   CHICAGO,    ROCK    ISLAND    &    PACIFIC 
RAILROAD 


Published  and  Printed  in  U.  S.  A.  by 
SIMMONS-BOARDMAN  PUBLISHING  COMPANY 

WOOLWORTH    BUILDING,    NEW    YORK 

CHICAGO  WASHINGTON  CLEVELAND 

CINCINNATI  NEW    ORLEANS 

LONDON 


COPYRIGHT, 

SlMMONS-BoARDMAN    PUBLISHING    COMPANY 

1921 


Press  of 

J.  J.  Little  &  Ives  Company 
New  York,  U.  S.  A. 


PREFACE 

The  authors  of  this  work  have  not  attempted  to  cover  the 
electric  welding  art  in  its  broadest  sense.  The  book  is  confined 
almost  exclusively  to  autogenous  electric  arc  welding. 

The  phenomena  of  the  welding  arc,  and  the  metallurgy  of 
welding,  are  in  such  a  state  of  development  that  the  authors'  in- 
formation has  been  limited  to  the  research  which  has  come  under 
their  observation.  Many  phases  of  these  subjects  have  been  left, 
therefore,  to  specialists  more  adequately  equipped  both  as  to 
electric  and  metallurgical  data  as  well  as  laboratory  apparatus. 
The  effort  has  been  made  to  present  information  that  is  most  in 
demand  for  practical  purposes. 

The  material  is  conveniently  and  logically  arranged  for  ready 
reference.  A  large  amount  of  practical  information  on  many 
phases  of  the  application  of  the  art  has-  been  incorporated ;  for 
instance,  descriptions  of  welding  systems  and  their  installation, 
phenomena  of  the  metallic  and  carbon  welding  arc,  training  of 
operators,  sequence  of  metal  disposition  for  various  types  of 
joints  and  building  up  operations,  electrode  materials  used,  weld- 
ability  of  various  metals,  weld  composition,  thermal  disturbances 
of  parts  affected  by  the  welding  process,  physical  properties  of 
completed  welds,  efficiency  of  welding  equipments  expressed  in 
pounds  of  metal  used  or  deposited  per  kilowatt  hours,  welding 
cost,  etc. 

It  is  desired  to  lay  particular  stress  on  the  fact  that  a  very 
small  percentage  of  the  possibilities  and  advantages  of  arc  weld- 
ing, from  an  industrial  standpoint,  are  being  made  use  of  at  the 
present  time,  and  if  this  work  will  result  in  a  broader  application 
of  the  art,  as  well  as  further  and  more  extensive  research,  the 
authors  will  feel  well  repaid  for  their  humble  efforts. 

The  book  is  based  largely  on  an  extensive  series  of  articles  by 

iii 


/:73729 


IV 


PREFACE 


the  authors  which  was  published  in  The  Railway  Electrical  En~ 
gineer.  Such  parts  of  these  articles  as  are  used  here,  however, 
have  been  thoroughly  revised  and  brought  up-to-date. 

THE  AUTHORS. 
Chicago,  111. 


CONTENTS 


PAGE 

PREFACE iii 

SECTION   I 

History  of  the  Evolution  of  Welding  Processes — Smith  or  Forge 
Welding,  Resistance  Welding,  Thermit  Welding,  Ox-acetylene 
Welding,  and  Electric  Arc  Welding I 

SECTION  II 

Equipment     for     Electric    Arc    Welding — Types     Used,     Operating 

Characteristics  and   Circuits 8 

SECTION  III 

Installation  of  Arc  Welding — Equipment — Welding  Accessories — 
Portable  and  Stationary  Equipment — Eye  and  Body  Protection — 
Cleaning  Devices,  etc 34 

SECTION  IV 

Electric  Arc  Welding  Principles — Circuit  Polarity — Arc  Heat — Arc 
Temperature — Arc  Current  and  Potential — Metal  Transfer,  etc.  .  54 

SECTION  V 

Training     of     Operators — Practice     Exercises — Sequence    of    Metal 

Deposition — Fusion — Penetration — Expansion   and   Contraction      .       69 

SECTION  VI 

Carbon  Arc  Welding — Metal  Cutting  by  Electric  Arc  and  by  Oxida- 
tion        97 

SECTION  VII 
Electrode  Materials — Composition — Specifications,  etc 107 

SECTION  VIII 

Preparation  of  Work  for  Electric  Arc  Welding — Various  Designs  of 

Welds — Types    of    Joints,    etc 125 

v 


vi  CONTENTS 

SECTION  IX 

PAGE 

Iron  and  Steel,  and  the  Welding  of  Each — Non-ferrous  Metals  and 
Their   Weldability 142 

SECTION  X 

Application  of  Arc  Welding  to  Railroads  and  Structural  Engineer- 
ing       •.     .     175 

SECTION  XI 

Miscellaneous  Notes  and  Arc  Welding  Data — Composition  of  Weld 
.  — Thermal   Disturbances — Physical    Qualities — Cost,    etc.     .      .      .     230 


LIST  OF  ILLUSTRATIONS 

FIG.    NO.  PAGE 

1.  Generator    Control    and    Auxiliary    Panel    Circuits    with    One 

Welding  Connection  on  Each 9 

2.  Generator   Control   and   Auxiliary    Panels 10 

2-A_    Electric  Arc  Welding  with  Fixed  Resistors n 

3.  Constant  Current  System  Circuit  and  Characteristic  Curves   .  13 

4.  Oscillograms    Showing    Effect    with    and    without    Reactor    in 

Circuit 15 

5.  Control  Panel  and  Welding  Generator  with  Motor  and  Reactor  16 

6.  Circuits  and  Characteristic  Curves  of  a  Variable  Voltage  Type 

Welder .  17 

7.  Circuits  and  Characteristic  Curves  of  Another  Variable  Voltage 

Type  Welder " 18 

8.  A   Self-Regulating   Motor-Generator   Welder 19 

9.  Characteristic  Curves  and  Circuits  for  a  Self-Regulating  Motor- 

Generator  Arc  Welder 20 

9-A.     Illustrating    How    Regulation    is    Produced   by    Shifting   the 

Line  of   Maximum    Potential   Difference 21 

9-B.     Modification  of   Design   Shown   in   Fig.   9-A 22 

9-C.    Another  Type  of  Welding  Generator  in  Which  Regulation 

is  Mainly  Produced  by  the  Armature 23 

9-D.     Characteristics  of  Generator  Shown  in  Fig.  9-C     ....  24 
9-E    Welding  Generator  with  Inter-Connected,  Separate  and  Self- 
Excited   Shunt  Field 25 

10.  A   Direct   Current  Welding   Converter 27 

11.  Circuit  for  a  Direct  Current  Welding  Converter 28 

12.  Constant  Energy  Arc  Welding  Set,  One-Man   Portable  Outfit, 

Norfolk   Navy   Yard f 29 

13.  Circuits    for   Equipment   Illustrated   in   Fig.    12 30 

14.  Alternating    Current    Equipment 32 

15.  Layout  for  Portable  Arc  Welding  Equipment  in  Roundhouses  36 

16.  A  Portable  Type  of  Arc  Welding  Equipment 37 

17.  A  Gas  Engine-Driven  Electric  Welding  Equipment  ....  38 

18.  Locomotive  Repair  Shop  Floor  Plan 40-41 

19.  Single  Operator  Stationary  Type  Welder  Mounted  on  a  Column  43 

20.  Helmet  and  Hand  Shields  for  Welding  Operators   ....  46 

21.  Operator  Equipped  with  Helmet,  Apron,  Gauntlet  Gloves  and 

Heavy  Closely-Woven  Shirt 46 

22.  Booth   for  Welding   Small   Miscellaneous   Parts 47 

23.  A  Portable  Screen  for  Welding  Operator .  48 

24.  A  Metallic  Electrode  Arc  Welding  Holder 49 

vii 


viii  LIST  OF  ILLUSTRATIONS 

FIG.    NO.  PAGE 

25.  Details    of   Fig.   24 50 

26.  An  Electrode  Holder  for  Carbon  Arc  Welding 51 

27.  Small  Sand  Blast  and  Roughing  Tool 52 

28.  Sketch  Showing  Polarity  of  Welding  Electrode  and  of  Work  54 

29.  Comparison   Between   Long  and   Short  Arcs 64 

30.  Penetration 66 

30-A.    Overlap 66 

31.  Instructions  for  Starting  and  Stopping  Individual  Type  Equip- 

ment         71 

32.  Diagram  for  Beginner's  Use  Showing  How  Connections  Should 

Be  Made 72 

33.  Methods  of   Striking  an  Arc .     .  73 

34-39.     Practice  Exercises  for  Training  Operators  to  Hold  an  Arc 

and  Follow  a  Given  Course 78 

40-43.  Adding  Metal  to  Joints,  Showing  Course  of  Electrode  and 

Method  of  Building  up  Metal 80 

43-A.  Fused  Zones,  Stressed  in  Parallel  and  in  Series  ....  84 

44.  Work  Marked  off  in  Sections,  Illustrating  Methods   of   Back 

Step     Welding 93 

45.  Strains  Produced  by  Cooling  of  Metal  in  the  Weld  ....  94 

46.  Adapter  Used  for  Low  Current  Valves  and  Intermittent  Welding  97 

47.  Correct  Position  of  Graphite  Electrode  and  Filler  Rod  ...  98 

48.  Edges  Joined  by  Melting  Together,  without  Use  of  Filler  Rod  99 

49.  Ragged    Edges    Produced    on    Plate    Material    when    Cut    by 

Carbon    Arc 102 

50.  Test  Pieces  for  Tensile,  Cold  Bend  and  Fatigue  Specimens   .  121 

51.  Test   Pieces   for   Impact   Specimens 122 

52.  Current    Carrying    Capacity    of    Welding    Carbons    .     .     .     .  124 
53-57-     Parts  to  be  Joined,  Showing  Effect  of  Expansion  and  Con- 
traction         127 

58.  Welds  Showing  Relation  of  Parts  and  Spacing 129 

59.  Showing  Free  Space  Necessary  for  Best  Welding  Results  .     .  130 

60.  Method  Used  Where  No  Free  Space  Can  Be  Allowed  at  Bottom  130 

61.  Method  of   Beveling 131 

62.  Reinforced    Weld    Section .131 

63.  Types    of    Joints 132 

64.  Position    of    Welds .     .  '"Y     ....  134 

65.  Kinds  of  Welds .     .     .     .     .  135 

66.  Types  of  Welds — Reinforced,  Flush  and  Concave 137 

67-70.     Preparing  Cylinders  and  Vessels  for  Welding  .     ...     .  140 
71-76.     Preparation   of   Longitudinal   Seams,    Pipes   and  Tubes   for 

Welding 140 

77.  Showing  Three  Kinds  of  Metal  in  Completed  Weld  .     .     .'    .  145 

78.  Broken    Cast    Iron    Locomotive    Cylinder    Showing    Fracture 

Partially    Welded 146 

79.  Method  of  Welding  Used  to  Avoid  Need  of  Machining  Through 

Heat-Affected  Zone 147 


LIST  OF  ILLUSTRATIONS  ix 

FIG.    NO.  PAGE 

80.  Fractured   Blades   Welded  to   Cast   Steel   Turbine  by  Electric 

Arc  Welding 161 

81.  Shaft  for  Excitor  Turbine  Welded  by  Metallic  Arc  Welding 

Apparatus 162 

82.  Sections   of   Piston   Rod   Built   up   by   Metallic   Arc — Showing 

Effect  of  Localized  Heat  and  the  Result  of  Annealing  .     .  165 
82-A.     Crank  Pin;    Metal  Added  with  Electric  Arc  without   Pre- 
heating   • 169 

82-B.     Crank  Pin;  Metal  Added  with  Electric  Arc  after  Preheating 

in  Blacksmith  Furnace 170 

82-C.     Crank  Pin ;  Metal  Added  with  Electric  Arc  after  Preheating 

with  Arc 171 

82-D.     Piston  Rod ;  Preheated  and  Metal  Added  with  Oxy-Acetylene  172 

82-E.     Piston  Rod;  Metal  Added  with  Oxy-Acetylene,  no  Preheating  173 

83.  Preparation  of  Door  and  Flue  Sheet,  Crown  Seams  and  Side 

Seams    for  Arc   Welding   New   Firebox 176 

84.  Method   of   Procedure   in   Welding  the   Four   Vertical   Seams 

on  a  Firebox *.  177 

85.  Numerical  Order  and  Direction  of  Welds .177 

86.  Side  Sheet  Joints  Welded  with  Electric  Arc 178 

87.  Joint  of   Crown   Sheet  Welded  with   Electric  Arc    ....  179 

88.  Two-Syphon  Application  to  Firebox  with  Combustion  Chamber  180 

89.  Diaphragm  Plate  Welded  in  by  Means  of  Electric  Arc  .     .     .  180 

90.  Proper    and    Improper    Reinforcement 181 

'  91.     Two  types  of   Door   Hole  Flange  Welds    . 181 

92.  Arc  Welded  Seam  across  Outside  Door  Sheet 182 

93.  Welding  Edges  of  the  Sheet  to  Mud  Ring  .     .           ....  183 

94.  Flue  Sheet  Hole  Countersunk  with  Flue  Set  Flush  ....  183 

95.  Fillet  Weld  Flue,  Extended  ........     .     .     .     .     .  183 

96.  Procedure  in  Welding  Beaded  and  Expanded  Flues   ....  184 

97.  Beaded  and  Expanded  Flues  Welded  by  Electric  Arc   ...  187 

98.  Section  of  Beaded  and  Expanded  Flues  Welded  by  Electric  Arc 

— with   and    without    Copper    Ferrule 187 

99.  Showing  Where  Cuts  Are  to  be  Made  When  Repairing  Various 

Parts    of    Firebox 188 

100.  Showing  Where  Cuts  Are  to  be  Made  When  Repairing  Front 

and  Back  of  Flue  Sheets 189 

101.  Patch   or   Flue    Sheet   and   around   Arch    Tube   Welded   with 

Electric   Arc 190 

102.  Front   Flue   Sheet   Joints   Welded   with   Electric   Arc    ...  191 

103.  Procedure  in  Welding   Side   Sheets 192 

104.  Procedure  in  Welding  Front  and   Back   Flue   Sheets    ...  1.93 

105.  A   Crown   Patch   Weld 194 

106.  Welding    Corner    Patches 194 

107.  Procedure  in  Welding  Crack  in  Knuckle  of  Back  Flue  Sheet  195 

108.  Repairing  Fractures  between  Rivet  Holes  at  Mud  Ring   .     .  195 

109.  Repairing  Fractures  by  Means  of  Disc 196 


x  LIST  OF  ILLUSTRATIONS 

FIG.    NO.  PAGE 

no.     Procedure  in  Applying  New  Door  Hole  Collar 197 

111-113.     Repairing  Corroded  or  Over-Size  Washout  Plugs    .      .     .  197 

114.  Repairing  an  Old  Riveted  Seam 197 

115.  Sleeve  of  a  Flexible  Staybolt  Welded  to  Sheet 197 

116.  Hatch  Cover  Corners  Welded  in  the  Navy  Yard 199 

117.  Spray  Shield  for  a  Gun,  Constructed  by  Electric  Welding  .      .  200 

118.  Rudder  for  a  Lake  Boat,  Repaired  by  Electric  Welding   .     .  201 

119.  Bracket  Constructed  and  Joined  to   Column  by   Metallic  Arc 

Welding 202 

120.  Peak    of    Truss    Showing    Members    Joined    by    Electric    Arc 

Welding 203 

121.  Members  of  the  Roof  Frame  Joined  by  Electric  Arc  Welding  204 

122.  Method  of  Welding  Horizontal  Locomotive  Frame  Member — 

Double    "V,"    Side    Position 205 

123.  Filling  Pieces  for  Five-  and  Six-Inch  Frames 206 

124-129.     Method   when   Work   Can   Be   Done   from    Both    Sides    of 

Frame  .  .  .  ,  >  .  .  . '  \ .  207 

130.  Method  of  Welding  Vertical  Member  of  Frame  Pedestal — 

Double  "V,"  Side  Position 208 

I3i-I35-  Procedure  When  Work  Cannot  Be  Done  from  Either  Side 

of   Frame 208 

136.  A  Completed  Weld  Using  Filler  Plates  in  Locomotive  Frame  209 

137.  Building  up  Flanges  of  Wheels  by  Arc  Welding  Process   .      .211 

138.  Working  Standards  for  Reclaiming  Axles  by  Electric  Arc  Weld- 

ing   212 

139.  Fracture  Prepared  for  Electric  Welding  .     .     .     .     .     .     .     .  213 

140.  Electric  Welded  Coupler  .     .     .....     ...     ,     .     .  213 

141.  A  Triple  Weld  in  Face  of  Coupler 214 

142.  An  Electric  Welded  Shank '  .     .     .     .  214 

143.  Built-up  Coupler  Shank 215 

144.  Method  of  Applying  Cast  Steel  Shims  to  Convert  6^/2  in.  Coupler 

Shank   to    9^    in 216 

145.  Fractured  Car  Bolster  Prepared  for  Electric  Welding  .     .     .  217 

146.  Welded    Fracture 217 

147.  How  Reinforcing   Plates   Are  Applied 217 

148.  How  Reinforcing   Plates   Are  Applied 218 

149.  Repairing    Cast    Steel    Side    Truck    Frame    by    Metallic    Arc 

Welding .     .     .     .  .219 

150.  Fractured  Cast  Iron   Cylinder  of  a  Mikado  Type  Locomotive 

Prepared   for  Arc  Welding 224 

151.  Welded  Cast  Iron  Cylinder  of  Mikado  Type  Locomotive   .      .  225 

152.  Journal    Box    Completely    Built   Up 226 

153.  Gear    Casing   Built   Up 226 

154.  Wheels   Cast  in    Separate    Parts   Assembled   by   Arc   Welding 

Process    (See   Fig.    155) 227 

155.  Wheels    Cast   in   Separate   Parts   Assembled   by   Arc  Welding 

Process    (See   Fig.    154) 227 


LIST  OF  ILLUSTRATIONS  xi 

FIG.    NO.  PAGE 

156.  Truck  Frame  and   Bolster  Built  up  by  Arc  Welding   Process  228 

157.  Truck  Frame  and   Bolster   Built  up  by  Arc  Welding  Process  228 

158.  Typical  Structure  of  Plate  Just  Below  Weld  (Magnified)    .     .  234 
159-  Typical    Structure    of    Plate    a    Slight   Distance    Below    Weld 

(Magnified) 235 

160.  Typical  Structure  of  Plate  Beyond  Influence  of  Weld   (Mag- 

nified)       235 

161.  Average  View  of  Deposited  Metal  of  Weld   (Magnified)    .     .  236 

162.  Streaks  of  Alumina  Inclusions  in  the  Steel  Plate   (Magnified)  237 

163.  Typical  Structure  of  Deposited  Metal  of  the  Weld  After  An- 

nealing at  900°    C.   for  Four   Hours   Showing   Oxide  and 
Nitride 238 

164.  Structure   of    Harrow   Zone   Between  Weld   and    Plate   After 

Annealing    as    Above,    Showing    Pearlite    and    Nitride    in 
Ferrite 238 

165.  Typical  Structure  of  Steel  Plate  Below  Weld  After  Annealing 

as  Above,   Showing  Pearlite  and   Coarse  Ferrite  without 
Nitride : .239 

166.  Typical  Structure  of  Deposited  Metal  of  the  Weld  as  Received, 

without  Annealing,  Showing  Round  Gray  Oxide  Spots  and 
Pale  Angular   Nitride   Crystals 240 

167.  Typical  Structure  of  Deposited  Metal  of  Weld  After  Anneal- 

ing at  500°  C.  for  Two  Hours,  Showing  Nitride  Needles 
Darkened  by  the  Etching  and  Round  Oxide  Dots  Unchanged    241 


ELECTRIC  ARC  WELDING 


EVOLUTION  OF  WELDING  PROCESSES 

There  are  several  methods  of  joining  metals  other  than  by 
means  of  mechanical  fastenings,  such  as  bolts,  clamps,  rivets, 
hinges,  etc.  The  first  form  of  jointure  known  to  man,  other  than 
the  above-mentioned,  was  fire  or  forge  welding  performed  by  a 
smith,  the  operation  consisting  essentially  of  heating  the  parts  to 
be  welded  to  the  proper  temperature  and  perfecting  a  union  by 
applying  pressure  by  means  of  hammer  and  anvil. 

As  pressure  welding  was  limited  in  its  application  man  en- 
deavored to  find  some  other  way  to  join  metals,  or  to  make  addi- 
tions of  metal  to  other  metal,  without  the  use  of  pressure.  He 
was  eventually  successful  in  this  endeavor  and  welding  without 
pressure  came  to  be  known  as  autogenous  welding,  so  called  be- 
cause of  its  self-  or  auto-generation ;  i.  e.,  it  is  self-produced  by 
the  application  of  intense  heat  without  any  physical  process  of 
compression  or  hammering. 

We,  therefore,  have  two  general  forms  of  welding — one  requir- 
ing external  application  of  pressure  to  complete  the  weld,  and  one 
in  which  the  weld  is  completed  without  the  external  application  of 
pressure.  In  the  first  form  the  union  is  secured  by  using  a  com- 
paratively low  heat  and  high  pressure.  In  the  second  the  union  is 
secured  by  a  relatively  high  temperature  without  the  aid  of  any 
external  pressure.  It  will  be  seen,  in  view  of  the  fact  that  weld- 
ing requires  actual  fusion  of  the  metals  joined  or  added,  that 
the  process  differs  inherently  from  those  methods  of  joining 
metals  known  as  brazing  or  soldering,  in  which  cold  surfaces  are 
united  by  the  interposition  of  a  fused  metallic  cementing  material, 
which  is  an  example  of  adhesion  rather  than  cohesion. 


WELDING 


Pressure  Welding. — The  conditions  for  successful  smith  or 
forge  welding,  which  is  a  form  of  pressure  welding,  may  be 
summed  up  as  clean  metallic  surfaces  in  contact,  with  a  suitable 
temperature  and  rapid  closing  of  the  joints.  All  the  variations  in 
the  forms  of  welds  are  due  either  to  differences  in  shapes  of 
material  or  to  the  different  practices  of  different  craftsmen. 

The  typical  weld  is  the  scarf;  the  joint  is  made  diagonally  to 
give  a  long  contact  at  the  point  of  union.  Abutting  faces  are 
made  slightly  convex.  The  object  is  to  allow  any  scale  or  dirt 
to  be  forced  out  which  if  allowed  to  become  embedded  in  the  joint 
would  impair  its  union.  It  is  important  to  have  the  proper  tem- 
perature or  else  the  metal  will  become  badly  oxidized  (burnt) 
and  will  not  adhere.  This  is  especially  true  in  the  case  of  steel 
welding. 

Resistance  Welding. — Resistance  welding  is  another  form 
of  pressure  welding  in  which  an  electric  current  is  made  use 
of  to  produce  the  welding  heat.  There  are  two  general  forms  of 
resistance  welding;  namely,  butt  and  spot,  the  name  in  each  case 
being  thoroughly  indicative  of  the  service  for  which  each  form  is 
particularly  adapted. 

Butt  welding  is  accomplished  by  having  the  surfaces,  or  parts 
of  the  metal  to  be  united,  fitted  approximately  to  each  other. 
Clamps  of  suitable  design,  generally  made  of  copper,  are  then 
attached  in  as  close  proximity  to  the  weld  as  is  practicable  and  in 
such  a  way  as  to  permit  the  desired  amount  of  current  to  pass 
through  the  parts  to  be  joined  or  welded.  The  resistance  offered 
to  the  passage  of  the  current  at  the  point  of  contact  produces  the 
welding  heat;  whereupon  sufficient  pressure  is  applied  to  effect 
the  union. 

.Spot  welding  also  utilizes  the  heat  generated  by  the  resistance 
offered  to  the  passage  of  an  electric  current  and  is  similar  to  butt 
welding  except  that  heat  is  generated  at  the  points  of  contact 
between  the  respective  electrodes  in  addition  to  the  heat  generated 
between  the  surfaces  to  be  united. 

Seam  welding  utilizes  the  heat  generated  in  a  way  quite  similar 
to  spot  welding;  in  fact,  it  is  an  extension  of  spot  welding.  A 
spot  weld  is  equivalent  in  form  to  flush  riveting ;  a  seam  weld  is  a 
non-interrupted  continuous  succession  of  spot  welds. 


EVOLUTION  OF  WELDING  PROCESSES  3 

All  forms  of  resistance  welding  require  primarily  a  heavy 
current  at  a  low  potential,  which  practically  necessitates  the  use 
of  alternating  current.  The  welding  equipment,  therefore,  gen- 
erally consists  of  a  step-down  transformer  with  a  regulating 
device ;  clamps  or  electrodes  for  making  the  electrical  connections 
to  the  work;  and  suitable  mechanical  parts  and  devices  for  sup- 
porting the  electrodes,  supplying  pressure  to  the  weld  and  sup- 
porting the  parts  to  be  welded. 

In  general,  it  may  be  said  that  the  resistance  form  of  welding  is 
best  adapted  to  standardized  operations,  especially  so  in  the  manu- 
facturing field  where  the  work  can  be  passed  through  the  machine. 
While  it  might  seem  that  the  application  of  this  form  of  welding  is 
somewhat  limited  there  is,  nevertheless,  a  vast  field  for  it  that  has 
not  yet  been  invaded. 

A  comparatively  recent  example  of  the  practical  application  of 
electric  resistance  heating  or  welding  is  that  of  rivet  heating, 
which  from  all  indications  will  soon  largely  supplant  the  fire 
method  of  rivet  heating.  The  rivet  is  heated  by  placing  it  between 
copper  electrodes  in  the  form  O'f  blocks.  A  heavy  current  is  then 
passed  through  the  rivet,  and  in  a  few  seconds  the  proper  heat  is 
attained.  The  riveting  and  handling  of  the  rivets  is  otherwise  the 
same  as  with  the  fire  method  of  heating.  Some  of  the  advantages 
of  the  electric  rivet  heater  are:  Better  control  of  heat  resulting 
in  fewer  rivets  burned ;  the  rivet  is  more  uniformly  heated,  thus 
reducing  the  chances  for  ineffective  riveting;  the  elimination  of 
smoke  and  dirt  results  in  better  efficiency  of  workmen ;  and  last, 
but  not  least,  the  fire  hazard  is  greatly  minimized. 

Thermit  Welding. — In  the  year  1894  it  was  found  that  the 
ignition  of  finely  powdered  aluminum,  mixed  with  metallic  oxides, 
produced  an  exceedingly  high  temperature  because  of  the  rapid 
oxidation  of  the  aluminum.  These  facts  were  turned  to  practical 
account  by  Dr.  H.  Goldschmidt,  who  welded  two  iron  bars  by 
molten  iron  produced  by  the  process  to  which  the  name  of 
"thermit"  is  now  commonly  applied.  This  process  has  been  won- 
derfully successful  and  has  been  extensively  used  especially  for 
welding  members  of  large  cross-sections  and  for  emergency 
repairs  on  certain  classes  of  work.  Thermit  welding  is  sometimes 


4  ELECTRIC  ARC   WELDING 

called  a  casting  process,  since  it  requires  a  mold  around  the  parts 
to  be  joined. 

Gas  Welding. — The  oxy-hydrogen  blowpipe  was  first  used 
about  the  year  1820  chiefly  for  producing  limelight.  It  was  also 
used  in  some  important  industrial  applications,  one  of  which  was 
the  fusion  of  platinum.  In  the  latter  part  of  the  nineteenth  cen- 
tury this  process  came  into  extensive  use  for  lead  burning,  or 
welding.  About  the  same  time  it  was  discovered  that  by  using 
oxy-acetylene  a  much  higher  flame  temperature  could  be  secured, 
which  together  with  improved  regulation  of  heat  control,  led  to 
the  extremely  rapid  use  and  extension  of  the  oxy-acetylene  torch 
to  the  welding  and  cutting  of  iron  and  steel,  and  other  metals  to  a 
lesser  degree.  While  other  gases  have  been  used  in  place  of 
acetylene,  the  oxy-acetylene  flame  is  by  far  the  most  widely  used. 
Today  the  oxy-acetylene  welding  and  cutting  process  is  used  in 
practically  all  of  the  metal  using  industries. 

Electric  Arc  Welding. — Electric  arc  welding  is  commer- 
cially  the  most  recent  and  newest  process  of  any  form  of  welding. 
Benardos  and  Slavianoff  are  generally  credited  with  the  discovery 
of  the  possibilities  of  the  carbon  arc  and  metallic  arc,  respectively, 
for  the  welding  of  metals.  The  carbon  arc  process  was  the  first 
one  to  be  used  for  welding  metals,  and  was  first  used,  on  a  small 
scale,  30  years  ago.  This  form  of  arc  welding  is  sometimes  called 
the  Benardos  process.  Not  long  after  the  carbon  arc  process 
was  demonstrated  by  Benardos,  Slavianoff  demonstrated  the  pos- 
sibilities of  the  metallic  arc  process,  but  it  was  not  until  compara- 
tively recent  years  that  either  was  used  to  any  appreciable  com- 
mercial extent. 

After  the  first  discovery  of  the  more  or  less  vague  possibilities 
of  electric  arc  welding  the  progress  in  the  development  of  the  art 
was  extremely  slow,  due  to  the  fact  that  it  was  only  with  great 
difficulty  that  the  work  of  development  could  be  carried  on. 
There  were  several  reasons  for  the  existence  of  such  a  condition, 
most  important  of  which  was  the  fact  that  the  men  who  first 
conceived  and  worked  to  develop  and  improve  the  welding  art 
were  apparently  versed  only  in  one  branch  or  phase  of  that 
science. 

It  must  be  borne  in  mind  that  to  develop  this  art  it  was  neces- 


EVOLUTION  OF  WELDING  PROCESSES  5 

sary  to  make  an  extensive  investigation  into  the  phenomena 
existing  in  the  arc,  both  carbon  and  metallic,  when  using  it  for 
the  fusion  of  metals.  No  matter  how  well  versed  a  man  may  be 
in  electrical  science  it  does  not  necessarily  follow  that  he  may 
understand  the  behavior  of  an  electric  arc  when  used  for  welding 
metals.  On  the  other  hand,  although  a  man  may  be  well  trained 
in  metallurgy  it  does  not  necessarily  follow  that  he  can  under- 
stand the  behavior  of  the  metals  when  subjected  to  the  tempera- 
ture of  the  electric  arc.  In  other  words,  the  electrical  men  did  not 
understand,  nor  were  they  thoroughly  acquainted  with  the  pecul- 
iarities manifested  by  the  electric  arc  when  used  in  conjunction 
with  molten  metal  during  the  welding  process.  And  the  metal- 
lurgical men  were  not  conversant  with  the  behavior  of  metals 
under  the  action  of  the  arc  stream  with  its  attendant  high  tem- 
perature variations. 

In  view  of  these  existing  conditions  it  was  necessary  that  much 
time  be  spent  in  research  work  by  both  electrical  and  metallurgical 
men.  Indeed,  it  was  not  until  the  electrical  phenomena  and 
metallurgical  phenomena  were  coordinated  that  a  real  beginning 
was  made  in  the  development  of  the  art  of  arc  welding.  And  not 
until  then  did  the  metal  using  industries  begin  to  see  the  possi- 
bilities of  its  use  and  to  lend  their  financial  assistance  to  its 
development. 

The  Electric  Arc. — If  two  carbons  which  are  connected  to 
a  sufficiently  powerful  electric  source  are  brought  together  and 
then  slowly  separated  the  current  will  not  cease  to  flow,  provided 
they  are  not  too  widely  separated.  Instead  an  arc  will  be  formed 
and  the  current  will  continue  to  flow,  since  the  vapor  formed 
between  the  two  carbons  serves  as  a  conductor  for  the  passage  of 
the  current  across  the  intervening  space.  The  temperature  of  the 
positive  electrode  of  a  carbon  arc  has  been  estimated  at  about 
7,500  deg.  Fahr.  If  an  arc  is  formed  between  two  metallic  elec- 
trodes the  temperature  will  be  somewhat  lower.  The  temperature 
of  any  arc  will  be  at  least  equal  to  the  vaporization  point  of  the 
materials  forming  the  electrodes.  In  electric  welding  the  heat  is 
communicated  to  the  metal  by  an  electric  arc.  In  one  method  the 
arc  is  deflected  from  the  space  between  the  carbon  electrodes  by  a 
magnetic  field.  In  this  case  the  metal  takes  no  part  in  the  con- 


6  ELECTRIC  ARC   WELDING 

duction  of  the  current;  the  heat  is  communicated  by  the  gases  of 
the  arc,  and  to  a  small  extent  by  the  radiation  from  the  hot  carbon 
electrodes  between  which  the  arc  is  formed.  This  particular 
method  was  inherently  not  a  commercial  success,  as  is  evidenced 
by  the  mechanical  impracticability  of  applying  the  arc  to  the  work. 
Also,  minute  particles  of  carbon  in  the  arc  stream  produced  by 
the  consumption  of  the  electrodes  were  deposited  in  the  weld, 
thereby  leaving  the  finished  weld  exceedingly  hard. 

The  form  of  carbon  arc  welding  generally  referred  to,  is  one  in 
which  .the  work,  or  part  on  which  metal  is  to  be  added,  forms  the 
positive  pole  of  a  direct  current  circuit,  and  an  arc  is  drawn  be- 
tween this  and  a  carbon  rod  to  which  a  handle  is  attached  for 
manipulating.  At  the  point  of  arc  contact  on  the  work  the  metal 
becomes  molten.  The  metal,  which  it  is  necessary  to  add  to  the 
weld,  is  supplied  by  melting  a  filler  rod  in  the  arc,  the  minute 
globules  of  molten  metal  commingling  and  fusing  with  the  molten 
metal  of  the  parts  to  be  welded.  In  this  method  the  bad  effects 
of  deposited  carbon  are  largely  eliminated  by  making  the  work 
positive,  in  which  case  the  current  flows  from  the  metal  to  the 
carbon  instead  of  from  the  carbon  to  the  metal,  as  was  the  original 
and  former  practice. 

A  constant  potential  source  of  current  supply,  together  with  a 
choking  resistance  in  series  with  the  heating  arc  so  arranged  as 
to  permit  an  adjustment  of  current  strength,  has  long  been  used, 
and  is  yet  to  a  considerable  extent.  Sufficient  potential  is  always 
required  (approximately  70  volts)  to  maintain  steadily  an  arc  of 
proper  length.  The  current  required  will  range  from  50  amperes 
to  600  amperes,  and  even  higher  in  some  instances,  depending 
upon  the  character  of  the  work. 

The  carbon  arc  process  has  been  limited  in  its  scope  of  applica- 
tion by  its  practical  confinement  to  down-hand  welding;  to  the 
tendency  to  oxidation  resulting  in  brittleness;  to  the  large  area 
heated,  resulting  in  the  bad  effects  of  excessive  expansion  and 
contraction,  loss  of  energy  or  heat  radiated  by  the  large  arc  area, 
and  conduction  by  the  metal  being  welded ;  and  the  necessity  of 
heavy  currents  with  the  cumbersome  equipment  required. 

During  the  past  two  years  much  has  been  contributed  to  the 
electric  welding  art.  Most  of  the  development  has  been  along  the 


EVOLUTION  OF  WELDING  PROCESSES  7 

lines  of  metallic  arc  welding,  consisting  of  improvements  in  equip- 
ments, electrodes  and  weld  protection,  which  has  in  turn  led  to  a 
more  intelligent  application  of  the  process,  and  the  resultant 
greater  extension  of  its  use. 

Metallic  arc  welding  consists  of  drawing  an  arc  between  the 
part  to  be  welded  and  a  metallic  electrode.  The  electrode  is  in 
the  form  of  a  wire,  or  small  rod.  It  may  or  may  not  be  of 
similar  composition  to  the  metal  which  is  to  be  welded.  The  arc 
is  established  by  striking  the  wire  electrode  to  be  fused  to  the 
work  with  a  dragging  touch  and  withdrawing  it  a  slight  distance, 
approximately  */%  in.,  forming  what  is  commonly  called  the 
metallic  arc.  This  form  of  arc  welding  differs  from  the  carbon 
arc  in  the  fact  that  the  filler  rod  or  wire  forms  one  terminal  of  the 
arc,  which  is  melted  and  is  conveyed  in  liquid  form  across  the  arc 
and  deposited  in  the  crater  on  the  work  piece,  which  forms  the 
other  terminal  of  the  arc. 

Due  to  the  fact  that  it  is  possible  to  project  metal  horizontally 
and  vertically  upward,  it  is  possible  to  do  welding  on  a  wall  or 
overhead  with  this  form  of  arc  welding,  something  which  is  not 
commercially  possible  with  the  carbon  arc.  This  feature  has  been 
a  contributory  factor  toward  making  the  metallic  arc  welding 
process  to  all  intents  and  purposes  universal,  and  gives  it  an 
extremely  wide  field  of  application. 

After  many  years  of  research  it  has  been  conclusively  demon- 
strated that  the  metallic  arc  welding  process  demands  a  certain 
close  coordination  of  the  equipment  and  the  arc  characteristic,  if 
the  best  results  are  to  be  obtained.  Great  strides  have  been  made 
in  the  perfection  of  welding  equipments  and  electrode  materials 
for  various  services. 

It  is  the  intention  of  the  authors  to  cover  the  requirements, 
design,  and  installation  of  electric  welding  equipments,  together 
with  a  complete  treatise  to  date  on  the  subject  of  electric  arc 
welding,  carefully  treating  each  phase  of  the  subject  in  turn,  and 
concluding  with  examples  of  detailed  application  to  the  various 
actual  operations  which  have  come  under  their  personal  obser- 
vation. 


II 

EQUIPMENT  FOR  ELECTRIC  ARC  WELDING 

Due  to  the  well-known  characteristics  of  the  electric  arc — that 
its  resistance  decreases  with  increases  in  current,  and  vice-versa — 
to  overcome  the  inherent  instability,  welding  arcs  must  be  con- 
nected in  a  circuit  having  a  drooping  volt-ampere  characteristic 
so  that  the  tendency  for  current  to  rise  or  fall  will  be  immediately 
countered  and  checked  by  reduction  or  increase  of  voltage  re- 
spectively. In  other  words,  variations  in  the  arc  current  should 
cause  the  arc  voltage  to  vary  in  the  opposite  sense.  Furthermore, 
each  arc  circuit  m'ust  include  its  own  independent  means  of  pro- 
ducing the  drooping  volt-ampere  characteristic,  the  properties  of 
the  arc  above  mentioned  absolutely  preventing  the  operation  of 
two  or  more  arcs  in  parallel  in  a  single  branch  circuit. 

When  electric  arc  welding  was  first  originated,  direct  current 
power  circuits  were  used  to  a  greater  extent  than  they  are  now. 
The  first  arc  welding  was  done  by  inserting  a  resistance  in  the 
supply  line  having  a  potential  of  125  or  250  volts.  Water  or  grid 
rheostats  were  used  as  resistance.  These  served  to  adjust  the 
voltage  to  approximately  the  proper  value  for  welding.  In  this 
scheme  the  power  wasted  was  considerable,  being  dissipated  in 
the  form  of  heat  in  the  rheostat  and  amounting  to  from  5  to  10 
times  as  much  as  that  consumed  by  the  arc,  when  a  metallic  elec- 
trode was  used.  In  certain  cases  of  welding  such  as  electric  rail- 
way work  where  the  power  is  taken  from  a  trolley  wire  through  a 
resistance,  approximately  95  per  cent  of  the  total  power  used  is 
wasted.  When  a  carbon  electrode  is  used  the  power  wasted  is  less 
since  a  greater  voltage  across  the  arc  is  required.  In  spite  of  this 
large  waste  of  power,  the  saving  effected  in  making  repairs  in 
many  industries  by  electric  welding  is  so  great  compared  to 
former  methods,  that  the  waste  is  more  than  offset.  This  form  of 
equipment  is  commonly  known  as  a  constant  voltage  system. 

8 


EQUIPMENT  FOR  ARC  WELDING  9 

Constant  Medium  Voltage  System. — In  the  evolution  of  arc 
welding  equipment  the  first  step  was  the  introduction  of  the 
constant  medium  voltage  type  which  consists  of  a  motor-generator 
and  a  control  panel. 

A  diagram  of  connections  for  controlling  a  generator  and  one 
welding  circuit  is  shown  in  Fig.  1.  The  motor  for  driving  the 
generator  can  be  furnished  to  operate  from  either  an  alternating 
or  direct  current  power  supply  at  any  commercial  voltage.  The 
generator  is  an  ordinary  compound-wound  commutating  pole 
type,  so  designed  as  to  give  a  constant  voltage  at  all  loads.  The 


Panel  for  Controlling  Generate 


>fer\\  

'  j    To  Auxiliary  Panels 
If  Used 


Comm.     Series 
Field        Field 


fleet. 


FIG.  i — Generator  Control  and  Auxiliary  Panel  Circuits  with  One  Welding 
Connection  on  Each 


generator  voltage  for  this  type  of  equipment  has  been  fixed  at  60 
volts  for  machines  up  to  600  ampere  capacity.  For  machines  of 
greater  capacity,  a  voltage  of  approximately  75  volts  is  provided. 
A  variation  of  the  voltage  will  cause  a  variation  of  heat  in  the  arc 
with  an  attendant  irregularity  of  deposited  metal  and  fusion.  The 
variation  should  not  exceed  five  per  cent. 

An  arc  welding  equipment  of  this  type  is  known  as  the  constant 
voltage  system,  and  is  distinct  from  some  of  the  recent  equipments 
as  more  than  one  operator  can  work  from  the  same  machine. 
-This  system  has  been  in  general  use  for  some  time,  usually  where 
a  number  of  operators  work  reasonably  close  together  and  where 
both  carbon  and  metallic  arc  welding  is  done.  When  more  than 
one  operator  is  required  a  control  panel  is  provided  for  each 
additional  operator.  A  diagram  of  connections  for  the  additional 


10 


ELECTRIC  ARC   WELDING 


or  auxiliary  panel  is  shown  in  Fig.  1.  On  each  panel  is  mounted 
an  adjustable  hand  rheostat  designed  to  permit  fairly  close  heat 
adjustments,  a  knife  switch  for  disconnecting  the  panel  from  the 
main  generator  circuit,  an  ammeter,  and,  in  some  cases,  protective 
relays  and  circuit  breakers  are  provided  to  prevent  error  in  using 


FIG.  2— Generator  Control  and  Auxiliary   Panels 

the  resistance  and  to  protect  against  overloads  by  short  circuit 
of  long  duration.  A  view  of  the  generator  control  panel  and  an 
auxiliary  panel  is  shown  in  Fig.  2. 

The  economy  of  the  constant  voltage  type  over  the  resistance 
welder  is  at  once  apparent  because  the  power  which  is  taken  from 
the  power  line  is  used  to  operate  a  motor  which  drives  a  generator 


EQUIPMENT  FOR  ARC  WELDING 


11 


to  provide  power  for  a  separate  and  independent  circuit  having  a 
medium  predetermined  voltage  value  not  greater  than  60  volts  for 
metallic  electrode  welding  and  75  volts  for  carbon  electrode 
welding. 

To  maintain  a  satisfactorily  stable  welding  arc  by  this  method, 
however,  requires  the  employment  of  resistance  of  such  value  that 
the  energy  expended  therein  equals  or  exceeds  that  usefully  em- 


O   ,  .   40  60  8O   '00       'SO        ZOO        ZSO        300       JSO       4Of 

FIG.   2-A— Electric   Arc   Welding    With    Fixed    Resistors 

ployed  in  the  welding  arc  and  the  operating  efficiency  becomes 
intolerably  low. 

Fig.  2-A  illustrates  the  conditions  existing  in  three  different 
welding  systems  employing  fixed  resistors  and  constant  voltage 
sources  of  current  wherein,  in  all  cases,  it  is  assumed  that  200 
amp.  at  20  volts,  or  4  KW,  are  usefully  employed  in  the  welding 
arc. 

Line  A  is  the  volt-ampere  characteristic  obtained  from  a  120- 
volt  source  with  a  resistor  of  0.50  ohm  included  in  circuit;  B  is 
the  characteristic  of  a  60-volt  source  with  resistor  of  0.20  ohm, 
and  C,  that  of  a  40-volt  source  with  resistor  of  0.10  ohm.  Curves 


12  ELECTRIC  ARC   WELDING 

A',  B'  and  C',  show  the  variations  in  arc  watts  resulting  from 
5-volt  variations  in  arc  volts,  above  and  below  the  normal  value 
of  20  volts,  in  the  systems  indicated  by  Curves  A,  B  and  C  re- 
spectively. 

In  the  120-volt  system,  with  4  KW  usefully  employed  in  the 
arc,  20  KW  are  lost  in  the  resistor,  thereby  giving  a  circuit  effi- 
ciency of  only  162/3  per  cent.  In  the  60-volt  system  8  KW  are 
lost  in  the  resistor,  making  the  circuit  efficiency  33  1/3  per  cent; 
while  in  the  40-volt  system  4  KW,  equalling  the  energy  usefully 
employed,  are  dissipated  in  the  resistor  and  the  circuit  efficiency 
becomes  50  per  cent.  These  efficiencies  will  not  be  realized  in 
operation,  however,  as  current  conversion  apparatus,  usually  in 
the  form  of  motor-generator  sets,  must  be  provided  to  develop 
the  voltages  chosen  and  this  necessity  introduces  other  losses 
which  further  reduce  the  operating  efficiency.  Motor  generators, 
suitable  for  supplying  a  single  arc  of  200  amperes  in  welding 
service,  flat  compounded  to  maintain  60  or  40  volts  on  the  line, 
would  probably  have  an  average  commercial  efficiency  of  65  per 
cent.  The  best  operating  efficiency  to  be  expected  of  the  60-volt, 
single  arc  system  would  therefore  be  about  22  per  cent  and  of  the 
40-volt  system  about  32  per  cent.  By  parallel  operation  of  two 
or  more  welding  circuits,  in  reasonably  close  proximity,  from  a 
single  motor-generator,  these  efficiencies  might  be  slightly  im- 
proved by  reason  of  the  higher  efficiency  of  the  larger  machine, 
but  unless  the  load  factor  was  maintained  at  a  desirably  good 
value  it  is  conceivable  that  the  efficiency  of  operation  might  fall 
below  that  obtained  from  a  corresponding  number  of  single 
circuit  machines  which  may  be  started  and  operated  just  as 
required. ' 

.Curves  A,  B  and  C,  of  Fig.  2-A,  show  that  making  steeper  the 
slope  of  the  volt-ampere  characteristic  improves  the  stability  of 
the  circuit  but  increases  the  energy  variations  in  the  arc  accom- 
panying variations  in  arc  voltage.  A  5-volt  departure  from  the 
normal  value  of  20  volts  produces  a  current  variation  of  only  10 
amperes  or  5  per  cent  in  the  120-volt  system,  25  amperes  or  \2l/2 
per  cent  in  the  60-volt  system,  and  50  amperes  or  25  per  cent  in 
the  40-volt  system,  with  energy  variations  in  the  arc  of  the  three 
systems  shown  by  Curves  A',  B'  and  C',  respectively.  Experi- 


EQUIPMENT  FOR  ARC  WELDING 


13 


ence  has  shown  that  it  is  necessary  in  the  40-volt  system  and  de- 
sirable in  the  60-volt  system,  to  include  reactance,  along  with 
the  resistance,  in  the  welding  circuit,  to  reduce  the  amplitude  of 
current  fluctuations  accompanying  voltage  fluctuations  inevitable 
on  the  welding  arc. 


20        40        60       QO        IOO       (SO       140       160       180       ZOO     Z2O 

Amperes. 

FIG.  3 — Constant  Current  System  Circuit  and  Characteristic  Curves 

Constant  Current  System. — A  modification  of  the  constant 
voltage  system,  commonly  known  as  the  constant  current  equip- 
ment or  system,  is  in  use  in  this  country.  The  principal  difference 
in  this  equipment  and  the  one  just  described  is  that  the  generator 
voltage  is  approximately  40  volts  instead  of  60,  and  the  resistance 
in  series  with  the  arc  is  automatically  adjusted  to  a  predetermined 
value  each  time  the  arc  is  established,  by  a  carbon  pile  regulator. 


14  ELECTRIC  ARC   WELDING 

The  diagram  of  connections  is  shown  in  Fig.  3.  The  tendency  of 
the  regulator  is  to  maintain  a  constant  current  within  a  certain 
range  of  arc  voltage.  Curves  O'f  the  volt-ampere  characteristics  at 
the  arc,  with  a  constant  generator  voltage  of  40  volts  and  a  con- 
stant current  regulator,  also  a  generator  voltage  of  60  volts  having 
a  fixed  resistance  in  series  with  the  arc,  are  shown  in  Fig.  3.  The 
40-volt  system  has  the  advantage  over  the  60-volt  system  for 
electrical  efficiency.  On  the  other  hand  the  40-volt  system  has 
the  disadvantage  that  it  is  more  difficult  to  establish  and  maintain 
the  arc.  Both  have  their  advocates  and  both  are  in  commercial 
use.  In  shops  where  both  systems  are  in  use,  the  majority  of  the 
operators  seem  to  favor  the  one  having  the  higher  voltage. 

For  either  system  the  arc  stability  can  be  made  satisfactory  by 
the  use  of  a  reactance  coil  of  such  capacity  as  to  enable  the 
operator  to  strike  the  electrode  on  the  work  and  withdraw  it  the 
proper  distance  before  sticking  of  the  electrode  occurs.  That  a 
reactor  is  effective  in  service  is  distinctly  indicated  by  oscillo- 
grams,  which  show  the  actual  characteristics  with  and  without  a 
reactor  in  the  circuit.  The  upper  curve  in  Fig.  4  was  taken  with 
no  reactor  in  the  circuit.  As  a  result,  the  operator  was  compelled 
to  strike  the  arc  three  times  before  he  was  able  to  establish  it. 
This  is  illustrated  by  the  three  peak  values  of  current.  The  lower 
curve  in  Fig.  4  was  taken  with  a  reactor  in  the  circuit.  This 
shows  that  the  current  reached  the  maximum  value;  the  instant 
the  arc  was  struck ;  however,  the  length  of  time  th^t  this  maxi- 
mum current  existed  was  so  short  that  there  was  no$tendency  for 
the  electrode  to  stick.  The  reactor  also  stabilizes  the  arc  and  pre- 
vents it  from  breaking  when  the  length  is  momentarily  slightly 
increased,  or  when  dirt  and  oxides  are  encountered.  Reactance 
coils  are  now  furnished  with  some  of  the  constant  voltage  systems. 
The  variations  of  current  and  voltage  shown  by  the  oscillograms 
are  produced  by  the  transfer  of  metal  from  electrode  to  plate  in 
globular  form,  the  current  increasing,  for  instance,  in  a  circuit 
of  this  characteristic,  by  the  short  circuit  of  each  globule  and 
decreasing  as  it  is  detached  from  the  electrode. 

Progress  Made  in  Developing  New  Equipment. — In  all  the 
equipment  so  far  described  more  or  less  power  is  wasted  because 
of  the  resistance  used  in  the  welding  circuit ;  in  order  to  minimize 


EQUIPMENT  FOR  ARC  WELDING 


15 


this  waste  it  was  necessary  to  use  a  voltage  as  low  as  possible  and 
still  permit  welding  to  be  done.  This  in  turn  necessitated  the  use 
of  extra  heavy  wires  for  distributing  the  power  to  the  different 
stations  in  a  shop  or  terminal,  thus  increasing  the  installation  cost 
greatly  providing  the  system  was  made  flexible,  which  is  necessary 
if  economy  in  welding  is  to  be  fully  obtained.  Out  of  this  condi- 
tion grew  the  demand  for  an  equipment  which  would  be  highly 


FIG.  4 — Oscillograms  Showing  Effect  with  No  Reactor  in  Circuit    (upper 
curve)  ;  with  Reactor  in  Circuit  (lower  curve). 

efficient,  not  only  for  eliminating  the  power  waste,  but  would  be 
light  enough  for  portable  use  when  conditions  demanded.  As  a 
result  of  this  demand  there  are  a  number  of  such  equipments  now 
on  the  market,  all  of  which  do  good  work  and  meet  the  require- 
ments to  a  greater  or  lesser  degree. 

There  are  many  conditions  to  be  considered  in  selecting  an  arc 
welding  equipment,  if  good  and  economical  results  are  to  be  ob- 
tained. It  is  therefore  the  intention  to  describe  a  number  of  the 


16 


ELECTRIC  ARC   WELDING 


different  equipments  and  systems  with  the  hope  that  the  informa- 
tion will  materially  assist  the  reader  to  select  suitable  equipment 
wisely. 


FIG.  5 — Control  Panel  and  Welding  Generator  with  Motor  and  Reactor 
(Single-Operator  Variable  Voltage  Type). 


Single-Operator  Variable  Voltage  Type. — The  more  recent 
developments  have  been  along  the  line  of  single-operator  equip- 
ments having  what  may  be  termed  self-regulating  characteristics. 


EQUIPMENT  FOR  ARC  WELDING 


17 


These  are  more  commonly  known  as  the  variable  voltage  type, 
made  so  by  suitably  designed  and  arranged  field  and  armature 
windings,  in  this  way  eliminating  the  resistance  in  series  with  the 
arc  and  increasing  the  efficiency.  Fig.  5  shows  a  self -regulating, 
variable  voltage,  single  operator,  150  ampere  arc  welding  equip- 
ment. The  diagram  of  connections  is  shown  in  Fig.  6.  A  stand- 
ard constant  speed  motor  is  used  for  driving  the  welding  gener- 


ZO        40        00        SO        100       IZO       140       160       180       ZOO 

A  mpe  re -s 

FIG.  6 — Circuits  and  Characteristic  Curves  of  a  Variable  Voltage  Type 

Welder 


ator.  Where  the  power  supply  is  alternating  current,  a  small 
generator  is  attached  to  the  armature  shaft  to  provide  direct  cur- 
rent at  a  constant  voltage  for  the  separately  excited  shunt  field. 
Where  the  power  supply  is  direct  current  the  exciter  generator  is 
not  required,  as  the  shunt  field  is  connected  across  the  power 
circuit. 

The  principles  involved  in  the  operation  of  the  welding  gener- 
ator includes  a  separately  excited  shunt  field  with  a  differential 
compound  winding.  When  the  generator  is  started  the  voltage  is 


18 


ELECTRIC  ARC   WELDING 


established  by  the  excitation  of  the  shunt  field  winding  P  and  it 
can  be  varied  by  the  small  field  rheostat  R.  When  an  arc  is 
struck  current  flows  from  armature  W  through  bucker  winding 
B;  the  bucker  being  of  opposite  polarity  to  the  shunt  field  winding 
reduces  the  effective  strength  of  the  shunt  winding,  thus  reducing 
the  generator  voltage  and  as  the  length  of  the  arc  is  decreased 
the  current  is  increased,  and  vice-versa.  If  the  heat  or  current  is 
not  the  proper  value  when  the  operator  establishes  a  satisfactory 


\ 


1000 




A,mp.e  re s. 

FIG.  7 — Circuits  and  Characteristic  Curves  of  Another  Variable  Voltage 

Type  Welder 

arc  length,  it  may  be  increased  by  shunting  current  around  the 
bucker  winding  by  closing  the  knife  switch  which  connects  shunts 
D  in  parallel  with  the  bucker  winding,  or  by  increasing  the  voltage 
with  the  rheostat,  or  by  both.  To  decrease  the  heat  this  operation 
is  reversed.  Fig.  6  also  shows  curves  for  the  volt-ampere  char- 
acteristics of  this  type  of  equipment.  The  reactance  coil  or 
stabilizer  5  is  in  the  arc  circuit  for  the  purpose  previously  stated. 
Another  equipment  is  in  use  similar  to  the  one  just  described. 
The  diagram  of  connections  is  shown  by  Fig.  7.  The  shunt  field 
in  this  case  consists  of  two  separate  windings ;  one  is  self-excited 


EQUIPMENT  FOR  ARC  WELDING 


19 


and  the  other  is  separately  excited.  The  heat  adjustment  is  made 
entirely  by  the  voltage  rheostats.  Referring  to  Fig.  7  the  lettered 
parts  are  named  as  follows  :  A,  welding  armature ;  B,  bucker  field ; 
E,  exciter ;  F,  separate  excited  shunt  field ;  F-i,  self-excited  shunt 
field;  H,  electrode  holder;  R  and  R-i,  voltage  adjusting  rheo- 
stats ;  S,  reactance  coil,  and  W,  work.  Fig.  7  also  shows  curves 
for  the  volt-ampere  characteristics  of  this  type  of  equipment. 


FIG.  8— A  Self-Regulating  Motor-Generator  Welder 

The  most  recent  development  in  the  self-regulating  type  of  arc 
welding  generator  is  a  self-excited  compound  wound  type,  and  is 
a  departure  from  all  previous  systems.  This  equipment  is  shown 
in  Fig.  8.  The  driving  motor  is  a  standard  constant  speed  motor 
of  from  5  to  10  h.p.  rating  for  metallic  arc  machines,  depending 
upon  the  capacity  and  efficiency  of  the  set.  The  variable  voltage 
feature  in  this  equipment  is  accomplished  by  distortion  of  the  field 
flux,  which  occurs  when  current  is  taken  from  the  armature  by 
drawing  the  arc.  The  diagram  of  connections  for  this  equipment 
is  shown  in  Fig.  9.  The  heat  adjustment  is  made  by  increasing 
or  decreasing  the  strength  of  the  shunt  field,  series  field,  or  both, 


20 


ELECTRIC  ARC   WELDING 


40 


with  the  current  adjusting  switch  or  voltage  adjusting  rheostat. 
The  lettered  parts  in  Fig.  9  are  as  follows :  A,  arc  welding  gen- 
erator; C,  current  adjusting  switch;  H,  electrode  holder;  S,  react- 
ance; V,  voltage  adjusting  rheostat,  and  IV,  work.  Fig.  9  also 


30 


Wa 


3000 
ZSOO 
2000 


4O 


8O 


240 


280 


I2O        IGO        ZOO 

A  m'peres    in  /Ire. 

FIG.  9 — Characteristic  Curves  and  Circuits  for  a  Self-Regulating  Motor- 
Generator  Arc  Welder 

shows  curves  for  the  voltage-ampere  characteristics  of  this  type 
of  equipment. 

Fig.  9-A  illustrates  the  manner  in  which  inherent  regulation  is 
produced  by  shifting  the  line  of  maximum  potential  difference 
around  the  commutator  and  away  from  the  collecting  brushes  to 


EQUIPMENT  FOR  ARC  WELDING 


21 


which  the  welding  circuit  is  connected,  in  response  to  current  in- 
crease through  armature  and  vice-versa.  0  F  indicates  the  field 
flux  developed  by  the  field  windings  and  producing  an  open  circuit 
voltage  distribution  around  the  commutator  represented  by  O  C, 
with  points  of  maximum  potential  difference,  in  line  with  the 
brushes,  indicated  as  60  volts.  Upon  closing  the  circuit,  current 
in  the  armature  will  produce  a  cross  flux — O  A.  OF  and  0  A 
combine  to  form  O  R,  the  resultant  flux.  As  O  F  remains  sub- 


FIG.  p-A — Illustrating  How  Regulation  is  Produced  by  Shifting  the  Line 
of  Maximum  Potential  Difference  around  the  Commutator  and  Away 
from  the  Collecting  Brushes 

stantially  constant  and  O  A  varies  in  proportion  to  line  current, 
increase  of  current  will  shift  O  R  and  consequently  the  points  of 
maximum  voltage  difference  on  the  commutator,  in  a  clockwise 
direction,  as  indicated  by  L,  and  the  voltage  effective  on  the 
brushes  will  fall  off.  On  the  other  hand,  decrease  of  current  will 
reduce  O  A,  shift  O  R  in  a  counter-clockwise  direction  and  conse- 
quently the  voltage  effective  on  the  brushes  will  rise. 

A  modification  of  this  design  employing  the  same  principle  for 
producing  the  variable  voltage  is  shown  by  Fig.  9-B,  together  with 
the  volt-ampere  characteristic  obtained  by  varying  the  open  cir- 
cuit voltage  by  a  single  rheostat.  In  this  arrangement,  field  ex- 
citation is  produced  by  self  and  separate  excited  shunt  fields.  The 


22 


ELECTRIC  ARC   WELDING 


strength  of  the  self-excited  field  will  obviously  be  reduced  when 
the  potential  is  reduced  at  the  welding  circuit  brushes  by  the  field 
flux  distortion  caused  from  the  cross  magnetization  force  pro- 
duced by  the  armature,  as  previously  explained. 

The  effect  of  the  decreased  excitation  force  is  to  reduce  the 
variation  of  arc  current  in  response  to  arc  potential  variation,  as 


rg 

60 

V.R. 
^ 

R 

wwv  

/Arc 

N 

^ 
F 

I 

J-? 

^- 

\ 

X 

X 

N 

•^ 

N 

^ 

\ 

\ 

s 

X 

\ 

x. 

\ 

50 

\ 

^ 

< 

x 

X 

A=  Arm 
F=Self 
Excited 

ature       Ra  Reactor 
•Excited  Field     Fl  -Separate 
Fi'eld    V.R=YariableResistance 

\ 

^ 

s 

^ 

v 

N 

. 

\ 

\ 

1^ 

\ 

N 

\ 

* 

\ 

\ 

\ 

s,^ 

^ 

x 

40 
30 

eo 

10 
n 

\ 

N 

\ 

\ 

\ 

\ 

\ 

\ 

s, 

\ 

\ 

X 

\ 

\ 

\ 

\ 

^ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

^ 

\ 

s 

N 

s 

\ 

\ 

\ 

\ 

\ 

^ 

\ 

\ 

\ 

\ 

\ 

\ 

s 

\ 

k 

\ 

\ 

\ 

S 

\ 

\ 

\ 

S 

\ 

V 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

V 

. 

\ 

> 

\ 

\ 

\ 

\ 

ss 

V 

\ 

^ 

\ 

\ 

\ 

\ 

S 

\ 

\ 

\ 

\ 

' 

^ 

V 

\ 

FIG.  Q-B — Modification  of  Design  Shown  in  Fig.  g-A. 


well  as  the  short  circuit  current  over  that  which  would  be  obtained 
should  the  strength  of  the  excitation  force  remain  constant. 

Another  modification  of  this  type  of  variable  voltage  generator 
is  one  in  which  two  shunt  fields  are  employed,  both  of  which  are 
excited  from  the  welding  armature.  In  this  case  one  field  is  con- 
nected across  the  welding  brushes  and  the  other  across  two  small 
brushes  so  located  on  the  commutator  that  when  the  line  of  maxi- 
mum potential  difference  is  shifted  around  the  commutator  the 


EQUIPMENT  FOR  ARC  WELDING 


23 


strength  of  the  latter  mentioned  field  will  be  increased  as  the 
strength  of  the  field  connected  across  the  welding  circuit  brushes 
is  decreased  in  response  to  increase  of  arc  current.  The  combined 
strength  of  the  two  fields  throughout  the  voltage  range  is  ap- 
proximately the  same  as  that  obtained  by  the  separate  and  self- 
excited  shunt  fields,  as  shown  by  Fig.  9-B. 

The  reaction  type  of  generator  for  arc  welding  will  respond  to 
variations  of  arc  resistance  with  great  rapidity.  The  rapid  action 
is  attributed  to  the  greater  rapidity  of  field  flux  distortion  over 


FIG.  Q-C — Another  Type  of  Welding  Generator  in  Which  Regulation  is 
Mainly  Produced  by  the  Armature 

that  obtained  by  variation  of  field  flux  density,  as  employed  here- 
tofore. 

Another  type  of  welding  generator  wherein  the  regulation  is 
mainly  produced  by  the  armature  is  shown  by  Fig.  9-C.  In  this 
type  of  generator  there  is  a  group  of  two  north  poles  followed  by 
a  group  of  two  south  poles.  There  are  two  fluxes  at  right  angles, 
the  horizontal  flux  being  called  the  main  and  the  vertical  the  cross 
flux.  In  operation  the  excitation  of  the  cross  poles  is  changed 
and  the  excitation  of  the  main  poles  is  held  constant  resulting  in 
variation  of  cross  flux  without  variation  of  main  flux.  The 
reason  for  this  independent  action  of  the  two  fluxes  lies  in  the  fact 
that  the  poles  are  symmetrically  located  and  thus  one  pair  of 
poles  belonging  to  one  magnetic  circuit  lies  at  points  of  equal  mag- 
netic potential  with  reference  to  the  other  magnetic  circuit. 

The  load  of  the  armature  is  taken  from  the  brushes  A  and  C 


24 


ELECTRIC  ARC   WELDING 


located  between  poles  of  opposite  polarity.  The  reaction  O  R 
of  the  load  current  may  be  resolved  into  two  components  at  right 
angles,  O  D  in  the  direction  of  the  main  poles  and  O  E  in  the 
direction  of  the  cross  poles.  The  component  O  D  supports  the 
main  flux  and  the  component  0  E  opposes  the  cross  flux.  Owing 
to  the  magnetic  structure  of  the  main  poles  being  saturated  the 
flux  through  the  main  poles  remains  practically  constant.  The 
cross  magnetic  circuit,  however,  is  not  saturated,  hence  the  com- 
ponent O  E  blows  out  the  cross  flux,  which  decreases  as  the  load 
increases.  Shunt  field  excitation  is  supplied  the  generator  from 


\\ 


40         80        120       160       220       240       280 
AMPERES 

FIG.   p-D — Characteristics   of    Generator    Shown   in    Fig.   Q-C. 

two  points  on  the  commutator,  which  possess  a  constant  differ- 
ence in  potential,  this  being  accomplished  by  a  third  brush  B, 
placed  between  poles  of  the  same  polarity  where  the  voltage  A-B 
remains  constant. 

A  series  field  opposing  the  cross  shunt  field  and  supporting  the 
armature  reaction  is  placed  on  the  cross  poles,  arranged  with  a 
system  of  taps  to  facilitate  adjustment  for  different  current  values 
in  steps  of  25  amp. 

The  generator  is  designed  to  give  at  no  load,  A  B  —  B  C  =  30 
volts,  hence  open  circuit  voltage  A  C  =  A  B  +  B  C  =  60  volts. 
Since  the  voltage  A  B  is  constant  and  B  C  decreases  with  the  load 
the  arc  circuit  voltage  A  C  must  decrease  with  an  increase  of 
current,  and  vice-versa.  At  a  predetermined  arc  current  the  cross 


EQUIPMENT  FOR  ARC  WELDING 


25 


flux  reverses  and  the  voltage  B  C  becomes  negative,  the  machine 
being  so  designed  that  this  occurs  at  the  maximum  arc  current. 
The  strength  of  the  series  winding  is  sufficient  to  limit  the  arc 
current  to  75  amp.  By  shunting  the  series  winding  the  active 
turns  may  be  decreased  to  obtain  an  increase  of  current  up  to 
the  capacity  of  the  machine. 

The  volt-ampere  curve  obtained  from  this  type  of  generator 
is  shown  by  Fig.  9-D. 

(The  section  relating  to  Figs.  9- A  to  9-D  inclusive  is  abstracted 


FIG.  9-E — Welding  Generator  With  Inter-Connected,   Separate  and   Self- 
Excited  Shunt  Field 

from  a  paper  presented  to  A.  I.  E.  E.,  June,  1920,  by  S.  R.  Berg- 
man and  H.  L.  Unland.) 

Inter-connected,  Separate  and  Self-excited  Shunt  Fields 
Welding  Generator. — Fig.  9-E  shows  a  scheme  of  inter-con- 
nected, separate  and  self-excited  shunt  field,  the  latter  acting 
accumulative  on  open  circuit  and  differential  on  short  circuit  to 
support  the  series  field  in  limiting  the  short  circuit  current  and 
current  variations  with  variation  of  arc  resistance.  The  volt- 
ampere  curve  obtained  from  this  type  of  generator  is  also  shown 
by  Fig.  9-E.  The  separate  excited  field  is  connected  through  the 
variable  rheostat  (V  R)  directly  to  the  exciter  terminals.  The 
reversing  shunt  field  is  connected  through  the  field  resistance  R  2 
to  the  generator. 


26  ELECTRIC  ARC   WELDING 

The  negative  terminal  of  the  exciter  is  connected  to  this  field 
winding,  whereas  the  positive  exciter  terminal  is  connected} 
through  the  interconnecting  resistance  R  I  to  the  positive  gener- 
ator terminal  B.  The  series  winding  always  opposes  the  separate 
winding.  When  the  generator  is  operating  under  no  load  (open 
circuit)  and  under  normal  welding  conditions,  the  current  through 
the  reversing  field  is  obtained  from  the  generator  terminals  in 
direction  indicated  by  arrows  marked  O  and  W.  Under  these 
conditions  this  field  is  self-excited  and  is  assisting  the  separate 
excited  field  to  maintain  the  generator  terminal  voltage.  When 
the  terminals  of  the  generator  are  short-circuited,  however,  as  in 
striking  the  arc,  then  the  current  through  the  reversing  field 
comes  from  the  exciter  circuit  through  the  interconnecting  resis- 
tance ;  thence  through  the  wire  connecting  points  A  and  B  as  indi- 
cated by  arrow  S;  thence  through  the  arc  circuit  and  the  reversing 
field  in  direction  of  arrow  S;  and  thence  to  exciter.  In  this  case 
the  reversing  field  opposes  the  separate  field,  thereby  assisting  the 
series  field  in  limiting  the  permanent  short  circuit  current. 

When  the  arc  is  being  operated  at  22  volts  we  will  consider  the 
total  accumulative  excitation  produced  by  the  separate  arid  re- 
versing field  as  100  per  cent,  out  of  which  71.7  per  cent  is  supplied 
by  the  former  and  28.3  per  cent  is  supplied  by  the  latter  field. 
When  the  generator  is  short-circuited  the  total  accumulative  ex- 
citation is  reduced  to  71.7  per  cent,  namely  the  separate  field, 
whereas  the  total  differential  excitation  is  34.5  per  cent,  out  of 
which  17.9  per  cent  is  supplied  by  the  bucking  series  field  and  16.6 
per  cent  is  supplied  by  the  reversing  field.  In  other  words  the 
latter  field  has  changed  from  28.3  per  cent  accumulative  to  16.6 
per  cent  differential  excitation  and  is  of  almost  as  much  assistance 
as  the  series  field  itself. 

The  open  circuit  voltage  obtained  from  self-regulating  equip- 
ments usually  ranges  between  45  and  75  volts.  The  ampere 
capacity  for  metallic  arc  welding  is  150,  200  and  300  amperes ;  for 
general  work  200  amperes  are  required.  An  ampere  rating  of  not 
less  than  300  amperes  is  required  for  carbon  arc  welding.  In 
considering  capacity  of  electric  welding  generators,  it  must  be 
borne  in  mind  that  in  speaking  of  a  150-ampere  or  200-ampere 
rating,  as  the  case  may  be,  it  is  meant  that  the  generator  shall  be 


EQUIPMENT  FOR  ARC  WELDING 


27 


able  to  supply  the  rated  current  to  meet  the  demands  of  an  experi- 
enced operator  working  continuously,  and  not  necessarily  a  con- 
tinuous rate  of  current  flow. 

Welding  machines  may  be  operated  where  electric  power  is  not 
available  by  driving  the  generator  from  any  constant  speed  power 
source  of  ample  capacity,  such  as  belting  to  a  line  shaft,  gasoline 


FIG.  10 — A  Direct  Current  Welding  Converter 

engine,  etc.    This  permits  the  application  of  arc  welding  at  almost 
any  location. 

Self-regulating  variable  voltage  equipments  have  been  devel- 
oped for  operation  from  a  constant  voltage  direct  current  circuit 
of  125  volts.  Fig.  10  shows  a  welder  of  this  type,  and  Fig.  11 
the  diagram  of  connections.  The  equipment  consists  of  one  arma- 
ture, one  commutator,  and  one  set  of  fields.  One  wire  of  the 
welding  circuit  connects  to  the  supply  line,  the  other  to  an  extra 


28 


ELECTRIC  ARC   WELDING 


brush  holder  on  the  commutator.  The  lettered  parts  in  Fig.  11 
are  as  follows:  A,  arc  welding  converter  armature;  C,  current 
adjusting  switch;  H,  electrode  holder;  S,  reactor;  V,  voltage  ad- 
justing rheostat,  and  W,  work.  This  equipment  merely  provides 
a  lower  variable  voltage  for  the  welding  circuit,  and  also  means 
for  heat  adjustment  without  the  use  of  any  series  resistance  in 
the  supply  line  or  welding  circuit;  in  this  way  a  high  efficiency 
is  obtained.  This  welding  machine  is  known  as  a  direct  current 
welding  converter. 

Another  welding  machine  which  operates  from  a  direct  current 
power  supply  of  125  volts  is  shown  in  Fig.  12.    This  welding  set 


FIG.  ii — Circuits  for  a  Direct  Current  Welding  Converter 

also  provides  a  lower  variable  voltage  feature  together  with  means 
of  heat  adjustment,  without  the  use  of  series  resistance  in  either 
the  motor  circuit  or  the  welding  circuit,  resulting  in  good  effi- 
ciency. The  equipment  is  simply  a  balancer  set  having  specially 
designed  field  windings;  a  diagram  of  connections  is  shown  in 
Fig.  13. 

These  equipments  are  better  suited  than  other  types  for  opera- 
tion from  125  volts  direct  current  supply,  when  available.  Their 
use  also  may  prove  economical  under  certain  conditions  by  pro- 
viding a  125-volt  circuit  by  using  a  motor-generator  set,  from 
which  a  number  of  converter  welders  or  balancer  sets  may  be 
operated;  in  other  words,  any  advantages  which  may  have  been 
offered  with  the  old  constant  voltage  multiple  operator  systems 
can  be  obtained  with  this  type  of  equipment  without  the  disadvan- 
tage of  having  to  provide  such  heavy  distributing  circuits  or  to 
tolerate  the  heavy  loss  of  power  in  resistance  ballast.  Also  the 


EQUIPMENT  FOR  ARC  WELDING 


29 


bad  effects  due  to  the  interruption  of  one  operator  by  another 
(more  or  less  experienced  when  more  than  one  operator  is  work- 
ing from  the  -same  circuit)  is  almost  entirely  eliminated.  The 
saving  effected  by  the  use  of  such  a  system  over  the  old  constant 
voltage  system,  would  in  a  reasonable  length  of  time  justify  the 
difference  in  the  first  cost. 

Competitive  claims  have  been  made  relative  to  the  quality  of 
welds  made  with  certain  controls  or  volt-ampere  characteristics, 


FIG.    12 — Constant   Energy  Arc   Welding    Set,   One-Man    Portable   Outfit, 
Norfolk   Navy  Yard 


stabilizing  characteristics,  etc.,  the  latter  often  being  referred  to 
as  long  and  short  arc  machines.  In  this  connection  a  great  deal 
of  commercialism  has  been  confused  with  facts  among  the  users 
of  arc  welding  equipments.  As  a  matter  of  fact  stabilizing  char- 
acteristics of  a  welding  circuit  are  as  necessary  for  good  welding 
as  a  short  arc,  and  this  may  be  obtained  within  the  machine  itself 
by  the  aid  of  a  reactance  coil  in  the  arc  circuit,  or  by  both.  Again 
the  shape  of  the  volt-ampere  curve  and  the  rapidity  with  which 
the  current  varies  in  response  to  variation  of  arc  resistance  will 
influence  the  arc  stability  and  ease  of  arc  establishment. 

The  tendency  for  the  electrode  to  stick  seems  to  increase  with 
an  increase  of  starting  current  above  the  normal  value,  and  the 


30 


ELECTRIC  ARC   WELDING 


tendency  of  the  arc  to  extinguish  seems  to  increase  with  a  de- 
crease of  arc  current  below  that  obtained  at  the  normal  arc  poten- 
tial. On  the  other  hand,  a  slight  increase  in  welding  current  with 
a  decrease  of  arc  potential  seems  to  facilitate  fusion  and  pene- 
tration. 

The  hypothesis  commonly  accepted  as  to  the  form  in  which  the 
metal  exists  in  passing  through  the  arc  is  that  it  exists  in  both 
gaseous  and  liquid  globular  form ;  it  is  estimated  that  85  per  cent 


Lines 


To  Electrode 


Jo  Work  Probably 
Grounded      " 


Shvnt  Field 

Comm.       Generator 
Field          Arma-fure 

FIG.  13 — Circuits  for  Equipment  Illustrated  in  Fig.   12 


Series      Comm.       

Field         Field    Armaiure      Field         Armerfure 


of  the  metal  is  transmitted  in  liquid  globule  form,  the  cycle  of 
globular  transfer  presumably  occurring  as  follows :  • 

A.  On  drawing  the  arc  liquefaction  of  the  electrode  end  begins. 

B.  On   continued   heating   the   electrode   end   expands    and   assumes   a 
globular  form. 

C.  With  the  continued  growth  of  the  globular  form  the  globule  short 
circuits  the  arc  stream  when  the  arc  voltage  drops  to  practically  zero 
value  and  the  arc  current  increases  to  short  circuit  value. 

D.  Heating    continues    under    short    circuit    conditions    until    liquefac- 
tion at  the  electrode  side  of  the  globule  exceeds  that  at  the  plate  side, 
when  due  to  the  greater  thermal  capacity  at  the  plate  the  molecular  at- 


EQUIPMENT  FOR  ARC  WELDING  31 

traction  and  surface  tension  of  the  plate  exceeds  that  at  the  electrode  at 
which  time  this  force,  plus  the  force  of  expanded  gas  within  the  electrode, 
affects  the  globule  detachment. 

E.  At  the  instant  of  detachment  the  current  decreases  while  the  voltage 
increases  until  the  initial  welding  current  flow  is  established  through  the 
arc  gases. 

The  high  rate  of  globular  transfer  is  shown  by  lower  oscillogram 
curve  of  Fig.  4,  where  the  current  peaks  can  be  seen  at  the  instant  the 
globule  short  circuits  the  arc  at  the  rate  of  approximately  25  times  per 
second. 

From  the  foregoing  it  appears  that  a  welding  circuit  should 
possess  the  following  characteristics  : 

1.  Ease  of  arc  establishment  when  the  work  piece  and  the  electrode 
are  cold. 

2.  Freedom   from  undue  tendency  to   sticking  or   freezing   of  electrode 
or   extinguishing   of   arc   with    maintenance   of    short   arc    stream. 

3.  Stable  arc  with  maintenance  of  short  arc  stream. 

4.  Limited  current  increase  with  growth  of  liquid  globule. 

5.  Limited  increase  of   current   at  the  instant  and  during  the   period 
the   globule    short   circuits    the   arc    stream.     An    increase   up    to    about 
50  per  cent  of  the  normal  seems  essential  for  adequate  penetration.     The 
increased  P  R  energy  replacing  to  a  considerable  extent  the  arc  terminal 
energy  lost  on  short  circuiting  the  arc  stream.    If  the  short  circuit  current 
is  too  great  the  tendency  for  the  electrode  to  overheat  due  to  occasional 
accidental  momentary  short  circuits  becomes  a  disadvantage.  • 

6.  To  facilitate  re-establishment  of  a  stable  arc  the  arc  voltage  should 
increase   rapidly  at  the  instant  of  globular   detachment  or   on   breaking 
a  momentary  short  circuit. 

A  study  of  the  curves  previously  referred  to  will  reveal  that 
about  the  only  difference  in  the  more  recent  variable  voltage 
equipments  and  a  constant  voltage  system  (where  a  resistance  is 
placed  in  the  arc  circuit)  is  that  the  straight  line  characteristic  of 
the  constant  voltage  welder  is  approximated  by  the  variable  volt- 
age welders.  The  other  merits  of  the  improved  equipments,  how- 
ever, are  of  great  value  and  have  been  an  important  factor  in 
furthering  the  application  of  the  process. 

Alternating  Current  Welding  Equipment. — Comparatively 
little  welding  has  been  done  in  this  country  with  alternating  cur- 
rent. It  has  been  utilized  to  a  considerable  extent  in  England  with 
coated  electrodes.  The  original  equipment  consisted  of  an  ad- 


32 


ELECTRIC  ARC   WELDING 


justable  ballasting  resistance  generally  constructed  for  operation 
from  100  volts.  Recently  special  welding  transformers  designed 
with  large  leakage  reactance  have  been  placed  on  the  market. 
The  general  scheme  of  the  reactive  method  of  control  is  shown  in 
Fig.  14.  In  the  operation  of  this  system  variable  voltage  is  ob- 
tained because  of  the  high  leakage  across  the  magnetic  shunt 
between  the  primary  and  secondary  windings.  On  account  of  this 
high  leakage  its  power  factor  is  low. 

The  use  of  coated  electrodes  greatly  assists  in  holding  an  alter- 
nating current  arc,  since  the  coating  tends  to  exclude  the  air  and 
prevent  the  arc  vapor  from  cooling  and  condensing  with  each 


•          FIG.  14 — Alternating  Current  Equipment 

reversal  of  the  current.  Where  a  bare  electrode  is  used  it  is  ex- 
tremely difficult  to  start  the  arc  (especially  so  on  cold  metal)  and 
it  is  difficult  to  sustain  the  arc  owing  to  the  effects  of  the  air 
each  time  the  current  reverses.  The  field  of  commercial  applica- 
tion of  the  alternating  current  arc  will  therefore  probably  be 
limited  to  small  installations  where  the  excessive  primary  capacity 
already  exists  and  for  use  with  coated  electrodes. 

While  there  are  other  makes  of  equipments  of  which  no  men- 
tion has  been  made  the  ones  described  represent  about  all  the 
principal  types  commercially  used. 

Selection  of  Equipment. — In  choosing  an  equipment  it 
should  always  be  borne  in  mind  that  in  a  process  where  the 
human  element  plays  as  important  a  part  as  in  the  case  of  auto- 
genous welding,  the  workability  of  the  arc  is  of  primary  impor- 


EQUIPMENT  FOR  ARC  WELDING  33 

tance,  and  should  be  such  as  to  minimize  as  far  as  possible  the 
human  element  which  under  the  best  conditions  when  welding 
day  in  and  day  out  finds  it  difficult  always  to  do  good  welding. 
Efficiency  can  probably  best  be  calculated  on  the  basis  of  kilo- 
watt hours  input  per  pound  of  metal  melted  with  the  equipment 
in  the  hands  of  an  experienced  operator. 

As  with  all  electrical  equipment,  the  safety  feature  must  not  be 
ignored.  This  is  especially  so  in  the  case  of  electric  welding 
equipments,  since  they  are  almost  invariably  placed  in  the  hands 
of  operators  who  are  entirely  unfamiliar  with  electrical  appar- 
atus. The  equipment  should  be  sc/  designed  that  the  welding 
operator  will  not  in  any  way  be  liable  to  injury  from  direct  or 
indirect  contact  with  the  power  supply  circuit.  The  local  welding 
circuit  to  be  entirely  safe  should  have  a  potential  as  low  as  con- 
sistent for  good  welding.  Past  experience  has  demonstrated  that 
welding  equipments  now  in  use  which  provide  a  separate  and 
independent  local  direct  current  welding  circuit  are  entirely  safe, 
their  potential  being  not  greater  than  75  volts. 


Ill 

INSTALLATION  OF  ARC  WELDING  EQUIPMENTS- 
WELDING  ACCESSORIES 

There  are  two  distinct  methods  for  distributing  power  to  arc 
welding  equipments.  These  may  be  classified  as  follows : 

(1)  The  standard  or  existing  power  circuit  may  be  used  to 
furnish  power  to  the  individual  equipments,  which  may  be  sta- 
tionary or  portable  as   conditions  demand.     If   stationary  they 
should  be  installed  in  the  same  manner  as  an  ordinary  motor. 
If  portable,  receptacles  should  be  located  at  various  points  from 
which  the  motors  of  the  welding  machines  are  to  receive  their 
power. 

(2)  A  separate  circuit  may  be  installed  to  furnish  power  at  the 
proper  value  from  a  motor-generator  set  or  other  means  operated 
from  the  main  power  circuit.    This  separate  or  secondary  circuit 
is  usually  designed  to  furnish  power  at  60-volts  to  a  number  of 
control  panels  located  at  different  points  within  the  area  to  be 
served. 

The  principal  difference  between  the  two  systems,'  as  far  as 
distribution  of  power  is  concerned,  is  the  cost  of  installation.  The 
individual  operator  equipments  as  a  rule  are  the  self-regulating 
type  using  no  resistance  in  series  with  the  arc  to  waste  the  power, 
which  is  not  the  case  with  the  latter  mentioned  system  of  distribu- 
tion, wherein  at  least  50  per  cent  of  the  total  power  used  is  con- 
sumed by  a  rheostat.  Therefore,  in  this  method  of  distribution 
the  circuits  would  be  required  to  carry  double  the  power  needed 
for  the  self-regulated  equipment,  in  addition  to  the  increased 
carrying  capacity  necessary  to  compensate  for  the  difference  in 
potential  of  the  two  systems ;  the  former  using  250  or  440  volts, 
the  latter  approximately  60  volts  for  distribution. 

The  field  for  the  lower  voltage  system  is  therefore  limited  to 
installations  where  the  cost  of  power  is  not  so  important,  where 

34 


INSTALLATIONS— ACCESSORIES  35 

the  waste  of  power  in  rheostats  may  be  lost  sight  of,  where  the 
average  load  factor  is  sufficient  to  utilize  the  capacity  of  the 
machine,  and  where  a  numjber  of  operators  are  working  reasonably 
close  together  so  that  but  little  copper  is  required  for  welding 
circuits ;  otherwise  the  low  voltage  which  is  used  with  this  system 
requires  an  excessive  copper  capacity  to  carry  the  comparatively 
high  current  when  it  is  necessary  to  distribute  the  power  over  a 
large  area. 

Stationary  and  Portable  Welding  Equipment. — There  are 
conditions  where  the  welding  equipment  must  be  brought  to  the 
work  if  full  economy  of  arc  welding  is  to  be  secured.  On  the 
other  hand  there  are  conditions  where  the  opposite  is  true,  or 
again  it  may  be  necessary  to  meet  both  conditions.  Generally  in 
manufacturing  plants,  a  very  large  per  cent  of  the  work  can  be 
brought  to  the  welding  equipment,  but  in  some  industries,  such  as 
ship  yards,  roundhouses,  car  yards,  etc.,  it  would  be  false  economy 
to  move  the  massive  work  to  the  welding  machines — for  instance, 
to  move  a  dead  locomotive,  car  or  other  heavy  structural  work 
the  cost  would  be  excessive  and  the  job  difficult. 

At  the  present  time  the  indications  are  that  a  system  of  both 
stationary  and  portable  welding  equipment,  operated  from  elec- 
trical power,  will  be  required  for  railroad  shops,  repair  yards, 
roundhouses  and  similar  layouts.  For  classes  of  -work  more  or 
less  isolated  from  a  source  of  electric  power,  as  for  instance  track 
work,  the  welding  equipment  may  be  driven  by  a  gas  engine.  If 
arc  welding  is  to  be  used  over  an  entire  railroad  system,  the  power 
supply  should  be  standardized  as  far  as  is  possible,  in  order  that 
the  equipment  (especially  the  portable  type)  may  be  transferred 
from  one  terminal  to  another  when  conditions  demand. 

Wiring  and  Installation — Typical  Layouts. — The  wiring 
around  railroad  terminals,  especially  roundhouses,  presents  a 
difficult  problem  mainly  on  account  of  the  gases,  and  the  cost  of 
maintenance  will  be  governed  largely  by  the  manner  in  which  the 
original  installation  is  made.  In  arranging  an  installation  it  is 
important  to  keep  in  mind  the  safety  features ;  for  instance,  where 
portable  equipments  are  used  it  is  necessary  for  the  outlets  and 
switches  to  be  of  the  approved  safety  type.  To  provide  ordinary 
protection  from  grounds,  provision  should  be  made  for  grounding 


36 


ELECTRIC  ARC   WELDING 


the  frame  of  the  equipment  when  in  operation.  Experience  has 
proved  that  car  yards,  roundhouses  and  other  similar  places  re- 
quire a  portable  type  of  equipment  for  the  reason  that  a  small 
amount  of  welding  is  done  and  in  almost  any  location  within  a 
comparatively  large  area. 

A  roundhouse  installation  for  portable  equipments  which  has 
been  found  very  satisfactory  over  a  period  of  more  than  two 
years,  is  shown  in  Fig.  15.  Power  outlets  are  located  every  100  ft. 
around  the  house.  With  this  spacing  the  extension  wires  from 


<5wifch  Cabinet  and 
•Safety  Type  £wifch 


Power  tfecepfac/e  and  Plug 

roundingf ffecepfac/e  and 'Plug 
Power  Conductor 


FIG.   15 — Layout   for  Portable  Arc  Welding   Equipment  in  Roundhouses 

the  welder  to  the  operator's  electrode  holder  will  never  be  greater 
than  150  ft.  and  ordinarily  75  ft.  will  be  sufficient.  For  metallic 
arc  welding,  cable  size  No.  1  B  &  S  is  large  enough  to  carry  the 
current  this  distance  safely  without  excessive  drop  in  voltage. 
The  twin  or  triple  conductor  cable  used  between  the  motor  start- 
ing switch  and  the  power  outlet  should  not  be  more  than  8  ft. 
long,  the  object  being  to  compel  the  operator  to  set  the  machine 
close  to  the  outlet,  preventing  his  laying  the  power  supply  cables 
across  the  aisle,  where  they  would  in  time  have  the  insulation 
damaged  which  might  result  in  injury  to  someone.  A  second 
plug,  or  an  auxiliary  contact  to  the  power  plug,  serves  to  ground 
the  frame  of  the  motor-generator  set.  •;.. 

When  an  operator  connects  a  portable  welding  machine,  he  first 
makes  sure  that  the  safety  type  switch  is  in  the  open  position  and 


INSTALLATIONS— ACCESSORIES 


37 


then  inserts  the  grounding  receptacle ;  the  power  plug  is  inserted 
next  after  which  the  safety  switch  is  closed.  The  machine  may 
then  be  started  by  the  motor  starting  box  mounted  on  the  truck. 
Where  the  power  supply  is  alternating  current  an  oil  switch 
equipped  with  overload  relays  is  used  for  starting  the  motor.  In 
disconnecting  the  machine  from  the  power  circuit,  the  motor 


FIG.  1 6— A  Portable  Type  of  Arc  Welding  Equipment 

starting  switch  is  opened,  then  the  safety  switch,  next  the  power 
.plug  is  removed  and  finally  the  grounding  receptacle  is  discon- 
nected. A  safety  switch  receptacle  and  grounding  device  com- 
bined is  now  on  the  market.  It  is  so  designed  that  the  circuit 
arrangement  is  automatically  taken  care  of  when  the  plug  is 
inserted. 

A  portable  type  of  arc  welding  equipment  for  use  in  a  round- 
house is  shown  in  Fig.  16.  This  equipment  is  made  weather- 
proof, providing  protection  against  the  steam  and  water  which 


INSTALLATIONS— ACCESSORIES  39 

usually  prevails  in  roundhouses.  The  same  feature  also  makes 
it  safe  for  operation  outside,  as  in  car  yards  where  it  may  be  sub- 
jected to  storms  if  left  out  of  doors  over  night.  A  reel  is  mounted 
on  the  truck,  on  which  the  secondary  extension  cables  are  wound. 
Collector  rings  at  each  end  serve  as  the  connections  between  the 
wire  cables  on  the  reel  and  the  positive  and  negative  terminals  of 
the  welder.  The  reel  provides  for  the  handling  the  wire  cables 
and  offers  much  to  their  protection.  This  method  of  roundhouse 
power  distribution  for  arc  welding  is  extremely  flexible;  its  cost 
is  nominal,  and  by  anticipating  the  future  capacity  requirements 
when  the  original  installations  are  made,  for  a  comparatively 
small  cost  additional  equipments  may  later  be  used  without  addi- 
tional installation  expense. 

A  freight  car  repair  yard  demands  practically  the  same  layout 
as  a  roundhouse.  As  a  rule  it  will  not  be  necessary  to  wire  the 
entire  yard  for  there  is  usually  a  certain  zone  within  which  all  the 
welding  may  be  done.  Also,  there  will  be  a  certain  class  of  work 
that  can  be  done  best  at  a  certain  station ;  such  a  station,  however, 
does  not  necessarily  demand  a  stationary  equipment,  as  it  can  be 
served  by  a  portable  type  which  may  be  used  elsewhere  when 
necessary.  When  electric  power  is  not  available  or  when  a  very 
small  amount  of  electric  welding  is  required  within  an  area  so 
large  as  to  make  it  almost  impracticable  to  wire  it,  even  if  electric 
power  is  available,  a  gas  engine  driven  equipment  such  as  shown 
in  Fig.  17,  may  be  used.  A  self-propelling  car  which  provides* 
power  for  arc  welding  is  now  being  developed  for  track  use. 
With  this  car  it  will  be  possible  to  build  up  worn  spots  in  track 
and  repair  bridges  and  track  accessories  in  a  terminal  or  on  a 
division  of  a  railroad. 

The  requirements  for  railroad  shops,  foundries,  ship  yards, 
reclamation  stations,  etc.,  will  be  governed  largely  by  the  local 
conditions.  For  instance,  in  railroad  locomotive  shops  and  other 
similar  places  it  is  not  only  necessary  to  be  able  to  do  welding  at 
almost  any  location  within  the  shop,  but  at  times  the  work  shifts  so 
as  to  require  a  number  of  operators  to  work  comparatively  close 
together.  To  meet  a  condition  of  this  kind  and  at  the  same  time 
utilize  the  equipments  to  the  best  advantage,  an  installation  of 
both  stationary  and  portable  equipments  seems  superior  to  any 


I 

in 


bj) 

£ 


42  ELECTRIC  ARC  WELDING 

other  method,  especially  when  the  floor  space  is  limited,  which  is 
usually  the  case. 

A  layout  for  an  arc  welding  system  installed  in  a  large  railroad 
shop  in  the  latter  part  of  1916,  which  is  representative  of  many 
other  similar  locomotive  and  passenger  car  shops,  is  shown  by  Fig. 
18.  The  main  distribution  circuit  in  this  shop,  which  is  250  volts, 
is  run  from  the  power  house  500  ft.  away.  From  this  circuit  are 
operated  20  single-operator  equipments,  11  of  which  are  station- 
ary and  9  portable.  In  the  pit  section  of  this  shop,  8  single- 
operator  equipments  are  mounted  overhead  on  brackets  attached 
to  the  columns,  in  the  same  manner  as  an  ordinary  motor  is  in- 
stalled. The  control  panels  for  each  machine  are  mounted  on  the 
same  column  which  supports  the  machine  platform,  low  enough 
to  be  within  reach  of  the  operator  as  shown  in  Fig.  19.  Three 
other  stationary  single-operator  equipments  are  included  in  this 
shop,  two  being  used  for  the  welding  of  miscellaneous  locomotive 
machinery  parts,  and  one  for  miscellaneous  tank  and  boiler  work. 
In  the  reclamation,  forge  shop  and  roundhouse,  there  are  7  other 
equipments  of  the  individual  operator  type  in  use,  making  a  grand 
total  of  27  in  the  entire  plant. 

Referring  to  Fig.  18  it  will  be  noted  that  the  rails  of  all  the  pits 
are  bonded  together  to  form  one  side  of  the  low  voltage  welding 
circuit  for  all  stationary  equipments  mounted  on  the  columns. 
The  other  wire  of  the  low  voltage  circuit  is  extended  from  each 
equipment  to  points  convenient  to  serve  at  least  six  pits.  Pro- 
visions are  made  for  connecting  to  this  wire  an  extension  cable 
(to  which  the  operator's  electrode  holder  is  attached)  at  four 
different  points  so  as  to  serve  the  six  pits.  If  the  work  within 
any  one  section  covered  by  the  stationary  equipments  requires 
more  than  one  arc,  the  additional  arcs  are  provided  with  the  port- 
able equipments  which  may  be  plugged  into  the  power  outlets 
located  between  every  other  pit.  If  within  a  limited  area  there 
is  not  sufficient  work  to  insure  a  fair  average  number  of  welding 
hours  per  day  for  an  equipment  then  that  particular  section  can 
best  be  served  with  a  portable  welder,  which  can  also  be  used  at 
any  other  point  in  the  shop,  in  this  way  utilizing  the  equipment 
to  the  best  advantage. 

In  reclamation  or  similar  shops  where  miscellaneous  welding  is 


INSTALLATIONS— ACCESSORIES 


43 


done  the  equipments  can  be  stationary,  and  if  a  number  of  oper- 
ators are  employed  continuously  a  multiple  operator  equipment 
may  prove  economical.  The  first  cost  of  a  multiple  operator 
equipment  will  always  be  less  than  the  same  capacity  in  single- 


FIG.  19 — Single-Operator  Stationary. Type  Welder  Mounted  on  a  Column 

operator  equipments;  where  there  is  comparatively  little  wiring- 
required,  and  the  cost  of  power  is  not  excessive,  their  use  may 
show  economy  over  the  individual  operator  equipments. 

In  concluding  the  subject  of  the  installation  of  arc  welding 


44  ELECTRIC  ARC   WELDING 

equipments,  it  might  be  well  to  emphasize  that  there  are  a  number 
of  factors  which  govern  such  installations  to  a  greater  or  less 
degree.  To  what  extent  these  factors  become  important  depends 
largely  on  the  local  conditions.  However,  in  general,  it  is  safe 
to  say  that  the  use  of  standard  power  circuits  for  the  main  dis- 
tribution, together  with  single-operator  equipments  (which  may 
be  portable  or  stationary,  as  conditions  demand)  will  prove  more 
satisfactory  than  any  other  method,  since  the  efficiency  of  an  arc 
welding  installation  will  be  determined  largely  by  its  flexibility 
and  also  by  the  workability  and  electrical  efficiency  of  the  welder 
which  the  individual  equipment  provides. 

Arc  Welding  Accessories — Eye  and  Skin  Protection. — The 
glare  emitted  by  an  electric  arc  is  exceedingly  intense ;  to  observe 
the  arc  used  for  welding  purposes  and  to  protect  the  eyes  and  skin 
from  the  harmful  effects,  shields  are  provided  with  special 
glasses,  the  preparation  of  which  has  required  considerable  re- 
search work  by  eminent  engineers;  scientists  and  surgeons  who 
have  defined  fairly  well  what  should  or  should  not  be  used.  Only 
persons  thoroughly  familiar  with  the  subject  should  be  allowed  to 
pass  on  glasses  to  be  used  for  arc  welding.  It  is  sufficient  to  say 
here  that  glasses  used  for  arc  welding  tone  down  the  erratic  glare 
of  the  visible  rays  sufficiently  to  permit  the  work  to  be  seen  rea- 
sonably clearly  and  also  exclude  the  invisible  infra-red  rays  and 
the  ultra-violet  rays.  Furthermore,  glasses  of  the  proper  color 
tints,  besides  softening  the  glare  .also  bring  out  the  details  more 
clearly.  Some  colors  or  color  combinations  amplify  this  to  a 
greater  degree  than  others.  This  can  be  determined  by  comparing 
different  colored  glasses  made  for  the  purpose.  Amber,  or  amber 
tinted  with  some  other  color  such  as  green,  are  the  most  common 
colors  in  general  use.  The  infra-red  rays  (sometimes  called  heat 
rays),  even  though  they  are  invisible,  can  be  detected  by  the  heat, 
which  is  generated  when  such  rays  are  subjected  to  a  material 
that  is  non-transparent.  To  guard  against  their  harmful  effects,  a 
glass  must  be  used  which  possesses  the  property  of  absorbing  or 
reflecting  heat. 

An  arc  produced  from  an  iron  electrode  is  rich  with  ultra- 
violet rays;  these  are  very  dangerous  to  the  eyes,  but  it  is  not  a 
difficult  matter  to  eliminate  their  effect  since  ordinary  clear  glass 


INSTALLATIONS— ACCESSORIES  45 

(not  quartz)  will  in  a  measure  furnish  the  necessary  protection, 
except  that  such  glass  does  not  have  the  qualities  for  eliminating 
the  intense  glare  present  in  an  arc.  For  that  reason  glasses  of  the 
proper  color  must  be  provided. 

There  are  a  number  of  special  safety  glasses  on  the  market 
which  meet  the  requirements.  One  type  possesses  the  properties 
of  toning  down  the  glare,  excluding  the  infra-red  and  ultra-violet 
rays,  besides  permitting  a  sufficient  degree  of  visibility.  Efforts 
have  been  made,  from  time  to>  time,  to  utilize  mica  for  eye  protec- 
tion, but  its  non-uniform  quality  prohibits  its  use.  Objects  viewed 
through  it  appear  blurred.  Because  of  the  cost  of  the  special 
glass  its  use  is  limited  in  many  localities,  so  that  glasses  or  com- 
binations of  colored  glasses,  which  give  results  approaching  the 
special  glasses,  are  extensively  used. 

A  combination  of  glasses  that  have  been  used  extensively  for 
arc  welding  consist  of :  one  emerald  green  (or  rich  bright  green)  ; 
one  or  two  ruby  (or  deep  red)  and  one  ordinary  clear;  one  or 
both  of  the  colored  glasses  must  be  of  the  heat  absorbing  or  re- 
flecting kind.  The  clear  glass  is  used  only  for  protecting  the 
colored  glasses  from  the  flying  particles  of  hot  metal. 

Experience  has  shown  that  the  depth  of  the  color  tint  required 
for  one  operator  is  not  satisfactory  for  another.  However,  the 
depth  of  the  color  tint  varies  in  the  commercial  glasses,  so  that 
advantage  is  taken  of  that  fact  to  enable  each  operator  to  select 
glasses  having  a  color  tint  favorable  for  his  eyes.  In  choosing 
glasses,  however,  care  should  be  exercised  in  selecting  a  color  tint 
as  deep  as  consistent  for  clear  visibility.  Only  glasses  that  are 
uniform  in  color  should  be  used.  If  streaks  or  spots  are  present 
the  glasses  should  be  discarded;  such  defects  may  cause  eye 
strain. 

The  glasses  referred  to  here  have  been  in  use  under  the  obser- 
vation of  the  writers  for  over  a  period  of  five  years  and  from 
service  test,  they  are  known  to  provide  proper  protection  when  it 
is  possible  to  select  them  free  from  the  imperfections  enumerated 
above.  Such  special  glasses  as  will  insure  the  user  a  uniform 
glass  free  from  optical  imperfections  and  which  will  provide  the 
proper  protection  for  the  operator  are  preferable  to  any  combina- 


46  ELECTRIC  ARC   WELDING 

tion  of  colored  glasses,  and  in  the  long  run  they  will  be  the  most 
economical. 


FIG.  20 — Helmet  and  Hand   Shields   for  Welding   Operators 

Helmets  and  Hand  Shields. — If  the  skin  is  exposed  to  the 
rays  of  a  welding  arc,  it  will  be  blistered  by  the  heat.  On  this 
account  the  shield  which  holds  the  glasses  must  be  large  enough 


FIG.  21 — Operator   Equipped   with   Helmet,   Apron,   Gauntlet   Gloves  '  and 
Heavy  Closely  Woven 'Shirt 

to  cover  the  entire  face.    Two  shields  that  have  been  found  satis- 
factory are  shown  in  Fig.  20.    The  holder  for  the  glasses  in  the 


INSTALLATIONS— ACCESSORIES 


47 


helmet  type  is  hinged  so  that  the  door  may  be  opened  to  enable  the 
operator  to  see  the  electrode  better  when  it  is  necessary  to  change 
it  or  to  observe  the  work  more  closely.  This  particular  feature  is 
shown  in  Fig.  21.  The  leather  apron  attached  to  the  bottom  of 


Back 


*] 


Lap  of 
Curtains 


Y 

*=*=*=*=^* 

^ 

i_i  —  i  _  1  —  i-i 

~lx^i          Table 
l_*3l                                           1  I 

tl—  j.  -rj-  i-fj 

*•  ^~~1|-* 

' 

;j5x 

Lap  of  Curtains 

1              •L.n-jtj      4Y   -C^ 

i 

Note:  Where  overhead  cmne service 
is  used,  provide  protection  for 
crane  operator 


Braces  4.  W.I.  Pipe 
)Vefdedin 


Front 


l" Rail  fitting 
Elbow  Side  Outlet 


Sewed 


Sewed 


Lapped 


I  Pipe  Flange 


Curtains,  8oz.  Duck  made  h 
3  pieces  iz"lap  at  back  cor- 
ners and  24  Lap  af  fronf. 
Pa'rnf  tv'tfh  No.  137 black painf. 


Table  fo  be  made  of-sitifab/e.       Boffom 
reclaimed  lumber.    Top  of      and  Ends, 
old  boilerplate. 


FIG.  22— Booth  for  Welding  Small  Miscellaneous  Parts 


the  helmet  serves  to  protect  the  neck  from  any  harmful  effects  of 
the  arc.  When  the  hand  shield  is  used  it  should  be  held  close  to 
the  face  to  prevent  reflected  light  from  entering  from  the  back  in 
such  a  way  as  to  permit  it  being  reflected  again  from  the  glass  to 
the  eyes.  The  helmet  type  shield  is  used  for  that  class  of  welding 
where  both  hands  are  required,  such  as  carbon  arc  welding  or 


48 


ELECTRIC  ARC   WELDING 


metallic  arc  welding  inside  a  firebox,  where  it  is  often  necessary 
to  use  one  hand  to  steady  the  body.  The  hand  shield  is  used  with 
light  work,  such  as  bench  welding,  etc.  The  glasses  use,d  for  such 
work  are  2  in.  by  4^  in.  and  are  of  single  strength  thickness. 
The  dimensions  should  be  uniform  in  order  that  the  glasses  will 
fit  properly  in  the  holder.  For  protection  of  the  hands  and  arms 
from  the  arc's  rays,  it  is  necessary  to  wear  gloves.  Canvas  gloves, 


FIG.  23 — A  Portable  Screen  for  Welding  Operators 

preferably  the  gauntlet  design,  will  serve  the  purpose.  Ordinary 
work  shirts  made  of  heavy  closely  woven  material  will  give  ample 
protection  for  the  arms  and  body.  Bellows  tongued  shoes  should 
be  worn  to  prevent  occasional  burns  of  the  feet  from  the  falling 
particles  of  hot  metal. 

The  subject  of  eye  and  skin  protection  from  the  welding  arc  is 
an  important  factor  in  the  arc  welding  process.  Workmen  un- 
familiar with  arc  welding  often  hesitate  to  become  operators 
because  they  know  of  some  one  who  unfortunately  has  had  his 
eyes  severely  burned  by  not  having  exercised  the  proper  precau- 
tions, which  may  or  may  not  have  been  his  own  fault.  Such  cases 


INSTALLATIONS— ACCESSORIES  49 

as  these  are  often  difficult  to  eliminate  from  the  minds  of  pros- 
pective operators.  They  can  only  be  eliminated  by  impressing 
upon  the  mind  of  the  beginner  that  it 'is  absolutely  necessary  to 
use  safety  devices  such  as  herein  described;  if  these  are  used 
properly  ample  protection  will  be  provided  for  the  eyes  and  body 
from  the  harmful  effects  of  a  welding  arc. 

Booths  and  Portable  Screens.— The  light  rays  which  shoot 
out  in  every  direction  from  a  welding  arc  give  an  illuminating 
effect  similar  to  that  produced  by  lightning  so  that  when  two  or 
more  operators  are  working  close  together,  or  when  other  work- 


FIG.  24 — A  Metallic  Electrode  Arc  Welding  Holder 

men  are  working  nearby,  each  operator  must  be  totally  or  par- 
tially surrounded  with  screens  in  order  that  this  light  will  not 
interfere  with  other  work ;  also  to  prevent  those  who  are  unfa- 
miliar with  the  process  and  its  effects  from  looking  at  the  arc. 

The  station's  or  booths  for  miscellaneous  work  consist  of  a  table 
having  a  metal  top  surrounded  with  curtains  such  as  shown  in 
Fig.  22.  For  the  class  of  work  that  cannot  be  brought  into  the 
booth,  portable  screens  such  as  shown  in  Fig.  23  are  required. 
All  screens  should  be  painted  black  in  order  that  they  will  not 
reflect  the  light  rays  from  the  welding  arc.  When  arc  welding  is 
a  new  feature  in  a  shop,  the  protective  apparatus  just  described 
will  be  required  to  a  greater  degree  than  will  be  the  case  after  the 
shopmen  become  accustomed  to  the  process,  at  which  time  shields 
of  every  description  such  as  pieces  of  sheet  metal,  boards,  etc., 
will  be  used  to  protect  workmen  in  the  near  vicinity  from  the 
direct  rays.  Screens  or  shields  are  also  advisable  to  shield  the 


50 


ELECTRIC  ARC   WELDING 


arc  from  air  drafts,  thus  reducing  the  difficulty  of  arc  manipula- 
tion and  reducing  the  effects  of  the  oxygen  and  nitrogen  of  the 
atmosphere. 

Electrode  Holders. — The  object  of  an  electrode  holder  is  to 
hold  the  electrode  firmly  so  as  to  permit  easy  manipulation  by  the 
operator  and  to  provide  a  means  for  the  flow  of  current  from  the 


JL 


faff  No.  D-1734        Brass 


FIG.  25— Details   of   Metallic  Electrode   Arc  Welding   Holder    Shown   in 

Fig.  24 


welder  terminal  to  the  electrode  without  excessive  heating  of  the 
holder,  which  may  be  caused  by  poor  contact  between  the  elec- 
trode and  the  holder.  Inferior  work  or  a  waste  of  welding  wire  is 
usually  the  result  of  overheating  at  the  point  of  contact  between 
electrode  and  holder  in  metallic  arc  welding.  If  the  welding  wire 
becomes  red  hot  between  the  end  being  melted  and  the  holder  the 
metal  will  not  flow  uniformly.  In  order  to  facilitate  manipula- 
tion of  the  welding  arc  the  cable  from  the  holder  must  be  ex- 


INSTALLATIONS— ACCESSORIES  51 

tremely  flexible  for  approximately  five  feet.  The  remaining  por- 
tion of  the  cable  only  needs  to  be  sufficiently  flexible  to  permit 
easy  handling. 

A  holder  of  a  well  known  type  for  metallic  arc  welding,  which 
has  been  designed  to  permit  frequent  cleaning  by  the  removal  of 
one  stove  bolt,  and  which  is  provided  with  five  feet  of  extra 
flexible  cable  is  shown  in  Fig.  24,  details  of  which  are  shown  in 
Fig.  25.  The  type  of  holder  is  simple,  inexpensive  and  light.  It 
has  been  in  use  for  some  time ;  it  gives  good  results  and  meets  the 
approval  of  a  large  majority  of  the  operators  who  use  it.  To 
apply  a  new  electrode  in  this  holder  it  is  only  necessary  to  insert 


FIG.  26 — An  Electrode  Holder  for  Carbon  Arc  Welding 

one  end  of  the  new  electrode  between  the  jaws,  then  by  prying 
the  jaws  further  apart  with  the  new  electrode  used  as  a  lever,  the 
stub  will  fall  out  and  the  new  electrode  will  be  held  firmly  in  place 
by  the  pressure  of  the  steel  spring,  the  tension  of  which  is  ad- 
justed by  the  stove  bolt.  Changing  electrodes  in  this  way  con- 
sumes the  least  possible  amount  of  time. 

A  type  of  carbon  holder  used  in  carbon  arc  welding  is  shown  in 
Fig.  26.  An  operator  manipulating  a  carbon  arc  is  subjected  to 
a  degree  of  heat  which  is  much  greater  than  that  developed  from 
the  metallic  arc.  Holders  for  the  carbon  arc  must  therefore  be 
larger  to  carry  the  heavy  current  and  to  provide  a  greater  dis- 
tance between  the  operator's  hand  and/the  arc.  It  is  also  neces- 
sary to  furnish  additional  protection  to  his  hand  by  equipping  the 
holder  with  a  large  heat  deflecting  disc  as  shown  in  the  illustra- 
tion. 


52 


ELECTRIC  ARC   WELDING 


Cleaning  Devices. — The  surfaces  of  the  work  on  which  weld- 
ing is  to  be  done  must  be  perfectly  clean  and  free  from  scale, 
rust  or  oxide.  It  is  not  always  an  easy  matter  to  prepare  the 
work  as  described,  but  to  assist  in  the  process  of  cleaning  various 
devices  are  being  used.  For  the  removal  of  light  loose  scale,  dirt 


M Hole  r'Diam.m 
*>r  Valve  Nut 


1 


'  Octagon  Steel,     Use  to  Remove  6cale, 
FIG.  27  —  Small  Sand  Blast  and  Roughing  Tool 


and  oxides,  a  steel  wire  brush  is  sufficient.  The  heavier  scale  and 
oxides,  such  as  mill  scale,  blue  oxide  produced  by  an  oxy-acetylene 
cutting  torch,  etc.,  require  a  sand  blast  or  roughing  tool  to  remove 
them.  A  small  light  sand  blast,  as  shown  in  Fig.  27,  is  preferable, 
as  it  can  be  taken  into  small  openings  and  used  in  close  places.  A 
useful  roughing  tool  for  loosening  scale  which  may  be  used  either 


INSTALLATIONS— ACCESSORIES  53 

in  connection  with  air  or  hand*  hammers  is  shown  in  the  same 
illustration.  The  use  of  such  a  tool  to  loosen  the  scale  and  a  wire 
brush  to  remove  it  provides  a  simple  and  convenient  method  for 
cleaning. 


IV 
ELECTRIC  ARC  WELDING  PRINCIPLES 

The  current  in  a  direct  current  electric  circuit  flows  in  a  definite 
direction;  namely,  from  the  positive  pole  of  the  source  through 
the  circuit  to  the  negative  pole.  When  a  circuit,  through  which  a 
sufficient  amount  of  current  is  flowing,  is  broken,  an  arc  is 
formed.  The  ends  at  the  break  become  heated  to  am  incandescent 
vapor ;  it  is  this  vapor  and  metal  particles  in  liquid  globular  form 
expelled  from  the  arc  terminals  that  forms  the  path  through  which 
the  current  passes  across  the  gap. 


FIG.  28 — Sketch  Showing  the  Polarity  of  the  Welding  Electrode  and  of 

the  work 

If,  for  example,  a  carbon  electrode  and  an  iron  plate,  as  shown 
in  Fig.  28,  are  connected  with  the  terminals  of  a  sufficiently  pow- 
erful source  of  electricity  and  the  carbon  is  brought  in  contact 
with  the  plate  and  is  gradually  separated  to  a  distance  of  about 
Y±  in. — the  direction  of  the  current  being  such  that  the  electric 
stream  leaves  the  plate,  passes  through  the  arc  and  enters  the 
carbon  rod  or  electrode — then  the  plate  will  be  the  positive  and  the 
carbon  rod  or  electrode  will  be  the  negative.  The  positive  elec- 
trode is  generally  indicated  by  a  +  (positive)  sign  and  the  nega- 
tive electrode  by  a  —  (negative)  sign. 

In  arc  lamps  used  for  producing  light,  the  ends  of  the  carbon 

54 


ELECTRIC  ARC  WELDING  PRINCIPLES  55 

electrodes  are  brighter  than  the  flame  between  them  and  the  car- 
bons are  of  unequal  brilliancy,  the  positive  carbon  being  much 
brighter  than  the  negative.  Moreover,  all  parts  of  the  end  of  the 
positive  carbon  are  also  unequally  bright ;  most  of  the  light  comes 
from  the  crater.  Since  the  light  giving  property  of  a  heated  body 
increases  rapidly  with  its  temperature,  an  inspection  of  the  arc 
will  show  that  the  crater  at  the  positive  terminal  is  the  hottest 
part  of  the  arc.  The  positive  electrode  is  often  referred  to  as  the 
anode,  and  the.  negative  electrode  as  the  cathode. 

It  is  estimated  that  at  least  75  per  cent  of  the  total  heat  of  the 
arc  is  liberated  at  the  positive  arc  terminal.  The  remaining  25 
per  cent  is  in  the  vapor  between  and  at  the  negative  arc  terminal. 
It  is  generally  believed  that  in  short  arcs,  such  as  are  used  in  the 
arc  welding  process,  more  heat  is  liberated  by  the  negative  arc 
terminal  than  by  the  arc  vapor. 

Polarity  for  Welding. — Owing  to  the  fact  that  the  greater 
quantity  of  heat  is  produced  at  the  positive  electrode,  it  is  neces- 
sary to  consider  the  matter  of  polarity  in  electric  arc  welding.  In 
metal  electrode  welding,  the  mass  of  the  piece  being  melted  is 
usually  less  than  the  mass  of  the  piece  to  which  the  metal  is  being 
added  so  that  the  amount  of  heat  lost  by  conduction  is  greatest  on 
the  latter  piece.  For  this  reason  it  is  made  the  positive  electrode. 
In  certain  cases,  such  as  the  welding  of  very  thin  sheet  metal, 
and  with  some  special  grades  and  types  of  electrodes,  the  wire 
electrode  is  made  the  positive  in  order  to  secure  better  welding 
characteristics  or  to  increase  or  decrease  the  arc  penetration. 

When  alternating  current  is  used  for  welding,  it  is  obvious  that 
an  equal  amount  of  heat  will  be  developed  at  both  terminals  of 
the  arc.  In  view  of  the  fact  that  an  equal  heat  is  imposed  on  the 
work  piece  and  on  the  electrode  being  consumed  in  the  a.c.  arc — 
instead  of  75  per  cent  at  the  work  piece  and  25  per  cent  at  the 
electrode  and  in  the  arc  flame,  as  in  the  case  of  the  d.c.  arc — it 
has  been  claimed  by  some  that  the  speed  of  welding  is  greatest 
with  the  a.c.  arc.  This,  however,  is  difficult  to  demonstrate  in 
practice,  due,  no  doubt,  to  the  fact  that  in  either  case  the  metal 
cannot  be  added  and  fused  to  the  work  any  faster  than  tfie  rate  of 
fusing  the  work  piece  will  permit.  It  is  well  known  by  those 
familiar  with  d.c.  welding  that  the  rate  of  depositing  metal  is 


56  ELECTRIC  ARC   WELDING 

greatly  decreased  when  the  current  value  is  insufficient  to  fuse 
the  work  piece,  even  though  the  current  may  be  sufficient  for  the 
electrode.  This  is  because  the  thermal  capacity  of  the  work  piece 
is  usually  greater  than  that  of  the  electrode.  It  would  seem  that 
a  direct  current  arc  has  certain  inherent  advantages  over  an  alter- 
nating current  arc  when  used  for  general  welding. 

Temperature  of  Electric  Arc. — If  a  vessel  of  water  is  heated 
so  as  to  permit  the  vapor  to  escape  into  the  air,  the  temperature  of 
the  water  will  not  increase  above  that  at  its  boiling  point,  namely 
212  deg.  Fahr.  under  ordinary  pressure.  Under  these  conditions, 
the  temperature  of  water  at  its  boiling  point  is  the  temperature  of 
its  volatilization.  This  is  a  general  law  for  volatilization  of  all 
substances  where  the  vapor  is  free  to  escape.  An  increase  in  the 
temperature  of  the  source  has  the  effect  of  accelerating  the  vol- 
atilization and  increasing  the  rate  of  the  formation  of  vapor.  In 
the  same  way  it  is  believed  that  the  temperature  of  the  positive 
electrode  or  crater  in  the  arc  is  thus  limited  to  the  temperature  of 
the  boiling  point  or  volatilization  of  the  substances  between  which 
the  arc  is  formed.  The  temperature  of  boiling  carbon  has  been 
estimated  at  6,300  deg.  Fahr. 

In  the  case  of  metallic  electrode  welding,  where  an  arc  is  drawn 
between  two  metallic  substances,  we  are  led  to  believe  from  the 
foregoing  that  the  temperature  of  the  arc,  which  will  vary  de- 
pending upon  the  kind  of  metal  used,  is  at  least  that  required  to 
volatilize  the  positive  electrode  to  form  metallic  vapor.  The  maxi- 
mum temperature  in  the  usual  converter  is  approximately  3,270 
deg.  Fahr.,  the  melting  point  of  the  steel  being  about  2,550  deg. 
Fahr.  The  boiling  point  of  steel  at  atmospheric  pressure  is  ap- 
proximately 4,440  deg.  Fahr.  The  temperature  of  the  electric  arc 
may,  of  course,  exceed  this. 

It  has  been  suggested  that  possibly  the  vapor  of  an  iron  arc  is 
superheated  by  combustion  of  some  of  the  elements  in  the  elec- 
trode or  parent  metal  when  exposed  to  the  atmosphere.  The 
maximum  temperature  of  the  metallic  arc  is  confined  to  a  very 
small  spot  in  the  positive  crater,  and  the  temperature  difference 
between  that  spot  and  the  edge  of  the  arc  flame  is  very  great.  It 
is  this  extreme  concentration  or  localization  of  the  heat  of  the 
electric  arc  that  reduces  the  losses  by  conduction  or  radiation  to 


ELECTRIC  ARC  WELDING  PRINCIPLES  57 

an  exceedingly  low  value.  A  certain  amount  of  material  vapor- 
ized is  oxidized  and  is  therefore  lost.  The  small  particles  of  iron 
oxide  (sometimes  called  iron  wool),  seen  floating  in  the  air  in 
the  vicinity  of  a  welding  arc,  come  from  the  arc  vapor.  Deposits 
of  this  iron  oxide  may  be  found  on  the  surfaces  of,  and  in  the 
vicinity  of,  the  material  being  welded. 

The  rate  of  formation  of  oxide  is  governed  largely  by  the 
extent  to  which  the  metal  is  exposed  to  the  air.  In  bare  electrode 
welding  the  amount  of  metal  lost  in  vapor  and  in  being  thrown 
out  of  the  arc  in  spherical  form  is  10  per  cent  to  15  per  cent  of 
the  electrode  material  used.  The  extent  to  which  the  arc  or  the 
vapor  column  is  exposed  to  the  air  will  also  affect  the  stability  of 
the  arc.  The  form  in  which  the  steel  exists  during  its  passage 
through  the  arc  in  metallic  arc  welding  is  at  present  the  subject  of 
much  investigation.  It  is  the  general  belief  that  the  metal  is  in 
minute  globules  or  in  a  stream  of  finely  divided  liquid.  This  con- 
clusion is  based  on  the  theory  that  there  must  be  an  interruption 
in  the  metallic  circuit  to  permit  the  formation  of  the  arc. 

Relation  of  Heat  and  Current  in  Arc  Welding. — The  electric 
arc  transforms  electrical  energy  into  heat.  One  kw.  hr.  of  elec- 
trical energy  is  equivalent  to  3,413  B.  t.  u.  Thus  an  arc  in  which 
the  current  value  is  150  amperes  and  the  voltage  between  elec- 
trodes is  20  volts,  tr'ans forms  3  kw.  of  electrical  energy  into 
10,239  B.  t.  u.  in  one  hour  of  continuous  operation.  Three  kw. 
hr.  of  electrical  energy  produces  the  same  amount  of  heat  as  may 
be  produced  by  approximately  6.6  cu.  ft.  of  acetylene  burned  in 
7.5  cu.  ft.  of  oxygen.  The  heat  is  localized  in  a  very  small  area 
in  electric  arc  welding,  and  fusion  or  welding  begins  at  the  instant 
the  arc  is  drawn  so  that  the  heat  loss  by  conduction  or  radiation 
is  exceedingly  small  as  compared  to  other  welding  processes. 
Present  practice  requires  a  maximum  power  demand  at  the  arc  of 
200  amperes  at  20  volts  per  operator  for  metallic  arc  welding. 
For  carbon  arc  welding  the  power  demand  at  the  arc  is  approxi- 
mately 300  amperes  at  about  35  volts.  If  extensive  cutting  is  to 
be  done  a  current  of  at  least  400  amperes  is  required.  The  ap- 
proximate current  and  voltage  required  for  the  various  sizes  of 
electrodes,  and  for  the  various  classes  of  work,  appears  elsewhere 
in  this  book. 


58  ELECTRIC  ARC   WELDING 

Influence  of  Air  Upon  Arc  Welding  Process. — When  an  arc 
is  formed  between  two-  carbons  a  dull  incandescence  can  be  ob- 
served, accompanied  by  a  bluish  lambent  flame  over  the  ends  of 
the  electrodes.  This  flame  is  similar  to  that  which  exists  over  the 
surface  of  a  hard  coal  fire  when  the  supply  of  air  is  insufficient 
and  is  due  to  the  burning-  of  the  carbon  vapor  in  the  oxygen  of 
the  surrounding  air.  It  is  believed  that  in  the  interior  of  this 
flame  little  or  no  oxidation  of  carbon  vapor  occurs,  because  the 
vapor  tends  to  fill  this  interior  space  and  therefore  displaces  the 
air.  This  is  analogous  to  the  welding  arc;  that  is,  the  molten 
metal  is  attacked  to  a  certain  extent  by  the  oxygen  and  nitrogen 
present  in  the  atmosphere  surrounding  the  arc.  Oxygen  attacks 
almost  all  metals  at  a  red  heat,  and  some  of  them  at  a  lower  tem- 
perature ;  and  under  the  temperature  and  conditions  of  the  weld- 
ing arc  iron  absorbs  nitrogen  readily. 

This  tendency  of  the  metal  to  oxidize  and  nitrogenize  is  very 
harmful,  and  leaves  the  metal  without  ductility,  so  that  every 
precaution  must  be  taken  to  minimize  these  effects.  Even  in  bare 
electrode  welding  much  can  be  done  to  protect  the  metal  in  the 
weld.  Among  the  most  important  things  are  to  work  always  on 
clean  metal  and  to  maintain  a  short  arc,  for  should  the  surface  of 
the  work  be  covered  with  dirt  or  scale,  the  arc  will  play  around 
and  will  therefore  be  unduly  exposed  to  the  air.  In  a  long  arc 
the  molten  metal  from  the  negative  electrode  must  travel  through 
a  long  heated  path  to  reach  the  point  at  which  it  is  to  be  deposited 
and  since  the  effect  of  oxygen  and  nitrogen  depends  upon  the 
temperature  of  the  metal  and  upon  the  time  to  which  it  is  exposed 
to  the  air,  the  resultant  oxidation  and  nitrogenization  of  the  de- 
posited metal  is  far  greater  than  if  a  short  arc  is  maintained. 

The  tendency  of  the  arc  to  extinguish  is  largely  due  to  the  effect 
of  the  surrounding  air,  for  should  the  vapor  column  be  increased 
sufficiently  from  the  proper  dimensions,  the  increased  radiation 
will  cause  the  vapor  to  condense  and  break  the  circuit,  thereby 
extinguishing  the  arc;  or,  should  the  dimensions  of  the  vapor 
column  be  maintained  constant  and  the  radiation  be  increased  by 
a  draft  of  air,  the  arc  will  likewise  be  caused  to  break. 

On  the  other  hand,  if  the  arc  is  enveloped  by  molten  slag  much 
of  the  air  will  be  excluded  and  the  arc  will  be  easily  maintained. 


ELECTRIC  ARC  WELDING  PRINCIPLES  59 

In  case  of  an  alternating  current  metallic  arc  the  effect  of  the  air 
is  very  noticeable  as  the  metallic  vapor  tends  to  cool  or  condense 
with  each  reversal  of  the  current.  To  sustain  an  alternating  cur- 
rent arc  where  a  bare  metallic  electrode  is  used,  a  voltage  of  at 
least  110  volts  is  required  and  even  then  it  is  difficult  to  maintain 
the  arc. 

Arc  Crater. — The  terminal  of  the  arc  formed  by  the  work 
piece  will  always  appear  as  a  crater  or  scalloped  shaped  depres- 
sion. This  crater  is  formed  possibly  by  volatilization  of  the  liquid 
metal  and  volcanic  action  due  to  the  release  of  occluded  gases  or 
by  the  gases  formed  from  the  elements  present  in  the  electrode 
or  parent  metal. 

The  crater  of  the  arc  under  certain  conditions  does  not  maintain 
its  position,  but  shifts  at  irregular  intervals  from  point  to  point 
over  the  surface  of  the  positive  electrode,  or,  in  the  case  of  weld- 
ing, over  the  work  or  the  part  to  which  metal  is  being  added. 
The  cause  of  this  shifting  is  explained  as  follows:  As  the  ma- 
terial is  consumed  the  crater  becomes  unequally  worn  at  different 
parts  and  the  arc  tends  to  be  established  at  the  point  where  the 
distance  is  the  least;  slight  impurities  or  irregularities  either  in 
the  wire  being  consumed  or  on  the  surface  or  in  the  metal  of  the 
part  to  which  metal  is  being  added  will  cause  a  shifting  of  the  arc, 
as  that  portion  of  the  metal  which  volatilizes  most  readily  tends  to 
become  the  center  of  the  crater.  As  the  length  of  the  arc  increases 
the  tendency  is  for  the  vapor  to  spread  laterally  in  all  directions 
over  the  surface  of  the  part  to  which  the  metal  is  being  added. 

In  carbon  arc  welding  where  the  filler  material  is  melted  in  the 
flame  between  the  arc  terminals,  the  arc  length  is  of  necessity 
greater  than  in  the  case  of  metallic  arc  welding,  so  that  it  is  diffi- 
cult to  maintain  the  positive  arc  crater  at  any  given  location  on 
the  work  piece.  This  shifting  of  the  arc  can  be  compensated  for 
in  carbon  arc  welding  by  delaying  the  melting  of  the  filler  rod 
until  the  area  on  the  work  piece  over  which  the  arc  plays  is 
heated  to  the  proper  state  of  fusion,  thus  permitting  fusion  be- 
tween the  added  and  the  parent  metal. 

In  metallic  arc  welding  the  filler  rod  forms  one  terminal  of  the 
arc  and  is  constantly  being  melted,  so  that  in  order  to  secure 
fusion  the  parent  metal  must  be  melted  simultaneously  with  the 


60  ELECTRIC  ARC   WELDING 

wire  electrode.  To  accomplish  this  it  is  necessary  to  provide  the 
proper  arc  current  and  maintain  a  uniform  short  arc  not  more 
than  J£  in.,  so  that  on  clean  work  the  arc  will  maintain  its  posi- 
tion at  one  location  for  sufficient  time  to  secure  proper  fusion  and 
penetration. 

Metal  Transfer  from  Electrode  to  Parent  Metal. — There 
have  been  a  number  of  theories  advanced  and  in  some  cases  sub- 
stantial evidence  to  support  them  as  to  the  force  which  causes  the 
transfer  of  metal  from  the  electrode,  in  metallic  arc  welding,  to 
the  parent  metal.  The  mystery  of  the  phenomenon  is  the  fact  that 
the  transfer  takes  place  regardless  of  direction  the  metal  must 
travel,  whether  downward  or  upward.  It  is  an  established  fact 
that  the  metal  in  the  arc  is  in  both  a  liquid  and  gaseous  form,  the 
metal  in  liquid  form  greatly  predominating.  A  summary  of  the 
research  so  far  conducted  on  this  subject  appears  to  credit  the 
arc  metal  and  vapor  transfer  to  : 

(a)  Expulsion   of   liquid   metal   and  vapor  by   expansion   of 
some  gas,  possibly  carbon-monoxide. 

(b)  Condensation  of  vapor  formed  from  electrode  material. 

(c)  Transfer  of  liquid  metal  by  molecular  attraction,  gravity, 
surface  tension,  adhesion  and  cohesion. 

The  authors  of  this  treatise  have  always  had  a  wholesome 
respect  for  the  molecular  theory,  owing  to  their  extensive  experi- 
ence with  practically  pure  iron  welding  electrodes,  which  when 
properly  made  appear  to  effect  the  transfer  of  metal  from  elec- 
trode to  plate  material  equally  as  well  as  materials  containing  gas 
forming  elements. 

AN  ABSTRACT  OF  AN  ARTICLE  ON  THIS  SUBJECT  IN  THE  ELECTRICAL 

WORLD,  JUNE  26,   1920,  BY  O.   H.  ESCHHOLZ,  RESEARCH 

ENGINEER,  FOLLOWS  I 

"The  flow  of  metal  from  a  wire  electrode  across  the  arc  to  the 
surface  of  the  fused  members  is  distinctive  of  metallic  electrode 
arc  welding.  The  phenomena  of  metal  transport,  therefore,  must 
be  of  fundamental  importance  in  the  determination  of  weld  and 
circuit  characteristics.  As  this  view  is  receiving  increasing  con- 
sideration by  electrode  manufacturers,  apparatus  designers  and 


ELECTRIC  ARC  WELDING  PRINCIPLES  61 

welding  engineers,  the  author  submits  a  few  pertinent  observa- 
tions with  the  hope  of  stimulating  further  discussion  and  investi- 
gation. 

'The  conversion  of  electrical  to  thermal  energy  is  a  well-known 
characteristic  of  the  arc.  The  concentration  of  this  energy  at  the 
terminal  of  the  wire  electrode  causes  an  intermittent  flow  of  metal 
across  the  arc  stream.  Careful  examination  of  the  performance 
of  a  variety  of  bare  electrode  wires  indicates  that  metal  transfer 
may  be  accomplished  in  part  by : 

"1.  Vaporization  and  condensation  of  electrode  material. 

"2.  Expulsion  of  vaporized  and  liquefied  metal  by  the  expansion 
of  gases  confined  or  generated  in  the  electrode  ends. 

"3.  Transport  of  liquefied  metal  due  to  the  forces  of  molecular 
attraction,  gravity,  surface  tension,  adhesion,  cohesion. 

"While  all  three  of  these  means  are  available  for  the  deposition 
of  metal,  it  is  the  author's  conclusion  that  under  good  welding 
conditions  at  least  85  per  cent  of  the  deposited  metal  is  trans- 
mitted in  liquid  form  through  the  action  of  molecular  forces. 

PROPORTION  OF  ELECTRODE  VAPORIZED  Is  SMALL 

"The  importance  of  this  factor  may  be  evaluated  by  determin- 
ing the  rate  at  which  the  filler  or  wire  electrode  metal  is  consumed 
and  comparing  the  energy  absorbed  at  the  bare  wire,  negative  elec- 
trode terminal  with  that  obtained  by  calculating  the  energy  neces- 
sary to  vaporize  an  equivalent  amount  of  metal. 

"It  has  been  found  by  test  on  welding  with  an  18-volt,  150-amp. 
arc  that  a  mild  steel  electrode,  5/32-in.  (3.9  mm.)  in  diameter,  is 
consumed  at  the  rate  of  3.1  Ib.  (1.4  kg.)  per  hour.  The  distribu- 
tion of  arc  voltage  is  estimated  to  be  as  follows:  Anode  drop,  9 
volts ;  cathode  drop,  7  volts ;  arc-stream  drop,  2  volts. 

"The  energy  input  at  the  negative  arc  terminal  is,  therefore, 
of  the  order  of  1,200,000  watt-seconds  per  pound  of  electrode 
metal.  The  energy  required  just  to  vaporize  one  pound  of  iron  is 
of  the  order  of  3,100,000  watt-seconds,  assuming  a  boiling  point 
of  2,450  deg.  C,  a  latent  heat  of  fusion  of  1,120  therm-grams  and 
a  specific  heat  of  liquid  iron  of  0.20.  It  is  at  once  evident  that 
under  normal*  welding  conditions  only  a  small  proportion  of  the 


62  ELECTRIC  ARC   WELDING 

electrode  metal  may  be  vaporized.  Overhead  welding  tests  in 
which  the  choice  of  electrodes  and  arc  length  were  such  as  prac- 
tically to  eliminate  metal  transfer  due  to  gas  expansion  or  molec- 
ular attraction  indicated  the  amount  of  metal  deposited  by  con- 
Energy 

Watt-Sees.      Per  cent 
Liquefaction    (2,000  deg.   C.)    of   90  per   cent  of 

wire  electrode  720,000  60 

Vaporization    (2,450  deg.   C.)    of    10  per  cent   of 

wire    electrode 310,000  26 

Radiation,  conduction,   convection  losses 170,000  14 


Approximate     energy     per     pound     of     wire 
electrode   consumed    1,200,000  100 

densation  to  be  of  the  order  of  5  per  cent.  A  reasonable  estimate 
of  the  distribution  of  negative  arc  terminal  energy  on  welding 
downward  appears  to  be  as  shown  in  the  table." 

Most  of  the  pencil  electrode  metal  appears  to  be  transported 
and  deposited  in  globular,  liquid  form  upon  either  welding  down- 
ward or  overhead,  when  the  electrode  current  density  is  of  the 
order  of  8,000  amp.  per  square  inch.  The  metal  transfer  appears 
to  be  accomplished  by: 

A.  Downward  Welding. 

(1)  Long  Arc.     Formation  and  growth  of  a  liquid  globule  at 
the  electrode  terminal  until  its  weight,  or  the  force  of  gravity, 
exceeds  the  sum  of  the  forces  of  surface  tension  and  cohesion 
which  tend  to  retain  the  globule  at  the  electrode. 

(2)  Short  Arc.    Growth  of  globular  end  until  contact  is  made 
with 'a  wetted  surface  (plate  metal  liquefied  by  anode  energy), 
the  forces  of  adhesion  and  surface  tension  at  the  plate  surface 
then  assisting  the  force  of  gravity  in  drawing  the  globule  to  the 
plate. 

B.  Overhead  Welding. 

(1)  Long  Arc.    Slight  deposition  due  only  to  condensation  of 
vaporized  metal  or  pellet  impact. 

(2)  Short  Arc.     Globular  growth  until  contact  is  made  with 
liquefied  plate  or  deposit  surface,  whereupon  the  forces  of  ad- 
hesion and  surface  tension  at  the  plate  overcome  'the  combined 


ELECTRIC  ARC  WELDING  PRINCIPLES  63 

forces  of  gravity,  cohesion  and  surface  tension  acting  to  hold  the 
globule  to  the  electrode  surface. 

Conditions  That  Affect  Resistance  of  Welding  Arc. The 

resistance  of  a  metallic  arc  (the  vapor  column  between  the  two 
electrodes)  like  that  of  all  ordinary  matter,  follows  Ohm's  law; 
that  is,  it  varies  directly  with  the  length,  and  inversely  with  the 
area  of  cross-section ;  consequently  if  the  area  of  the  vapor  could 
be  maintained  as  the  length  of  the  arc  is  increased,  the  resistance 
of  the  column  would  vary  directly  with  its  length.  This,  how- 
ever, is  seldom  the  case,  for  as  the  length  of  the  arc  increases  the 
tendency  is  for  the  vapor  to  spread  laterally  in  all  directions,  in- 
creasing its  cross-sectional  area;  it  sometimes  happens  that  the 
increase  in  the  resistance  caused  by  the  increase  in  the  length  of 
the  arc  may  be  more  than  compensated  by  the  decrease  in  its 
resistance,  due  to  the  enlargement  of  the  area  of  the  cross-section. 

If  the  current  passing  through  an  arc  is  maintained  constant, 
the  pressure  at  the  terminals  of  the  arc  is  always  increased  by 
increasing  the  distance  between  the  electrodes.  The  apparent 
resistance  of  the  arc  is  always  increased  by  an  increase  in  its 
length.  All  of  this  increase  may  not  be  exactly  proportional  to 
the  length,  owing  to  the  tendency  to  lateral  spreading.  If  the 
distance  between  the  electrodes  is  maintained  constant  and  the 
current  through  the  arc  is  increased,  then  the  apparent  resistance 
of  the  arc  may  either  increase  or  diminish.  It  will  usually  de- 
crease. TB 

In  view  of  the  foregoing,  it  is  obvious  that  a  slight  increase  in 
arc  length  may  or  may  not  reduce  the  heat,  depending  not  only 
on  the  area  of  the  arc,  but  also  on  the  characteristics  of  the  weld- 
ing apparatus  which  regulates  the  welding  current.  In  the  case  of 
a  machine  which  tends  to  maintain  a  constant  current  flow  re- 
gardless of  the  arc  length,  the  power  transformed  into  heat  by  the 
arc  would  be  increased  with  an  increase  in  the  length  of  the  arc, 
whereas  the  so-called  constant  watt  or  constant  heat  machine 
may  reduce  the  heat  in  the  arc,  when  the  length  of  the  arc  is 
slightly  increased.  In  either  case  the  metal  deposited  with  a  long 
arc  is  always  brittle  and  appears  to  be  burnt.  Furthermore,  it 
does  not  unite  with  the  work  or  mass  being  welded. 

Arc  Length.— The  arc  length  will  govern  largely  -the  extent 


64 


ELECTRIC  ARC   WELDING 


to  which  the  metal  is  affected  by  the  atmosphere,  the  fusion  or 
penetration,  over-lap,  and  arc  function ;  i.  e.,  the  smoothness  with 
which  the  metal  flows  and  the  ease  of  directing  the  flow.  As 
these  are  among  the  most  important  considerations  for  good 
welding  the  importance  of  the  proper  arc  length  is  evident. 

For  example,  in  the  metallic  arc  the  metal  is  conveyed  in  both 
liquid  and  vapor  form  across  the  arc.  With  the  shortest  possible 
arc  that  can  be  maintained  the  added  metal  suffers  from  the 
effects  of  the  oxygen  and  nitrogen  of  the  atmosphere.  It  is, 
therefore,  evident  that  if  the  arc  length  is  excessive,  the  effect 
of  the  atmosphere  will  be  increased  in  proportion  to  the  increased 


Improper 
Arc  Length. 


JL. 


T 


Long  Arc 


u 


Proper 
A  re  Length. 


Long  Arc  "Constantly  Shifting  on 
Plate  Causing  Poor  Fusion  and  ex- 
cessive Oxidation. 


Short  Arc~  Concentrated  Insures 
Proper  Penetration  with  Minimum 
Oxidation. 


FIGS.  29  and  29- A — Comparison   Between  Long   and   Short   Arcs 

time  the  heated  metal  is  exposed  in  traversing  the  long  arc. 
Furthermore,  it  is  believed  that  some  of  the  air  is  excluded  by  the 
gas  surrounding  the  arc  formed  from  the  elements  in  the  electrode 
and  plate  material.  If  this  theory  is  correct  the  arc  enclosure 
would  obviously  be.  more  complete  with  a  short  arc  than  with  a 
long  one,  as  in  the  latter  case  the  air  drafts  would  soon  displace 
the  major  portion  of  the  gas  film  about  the  arc.  The  penetration 
and  overlap  may  be  considered  as  proper  fusion  of  the  parent 
metal  and  this  is  governed  by  the  concentration  of  the  total  heat 
energy  liberated  in  the  arc,  since  some  of  the  heat  of  the  liquid 
deposit  and  arc  flame  serves  to  melt  the  parent  metal. 

The  heat  concentration  on  the  plate  metal  in  a  short  arc  is  at  a 
maximum  and  the  heat  losses  in  the  arc  stream  are  at  a  minimum, 
with  the  result  that  effective  fusion  is  secured. 

The  heat  losses  from  the  arc  stream  are  increased  with  a  long 
arc.  The  arc  will  shift  constantly  on  the  plate  metal  and  the  total 


ELECTRIC  ARC  WELDING  PRINCIPLES  65 

heat  will  not  be  sufficient  to  effect  the  crater  necessary  for  proper 
fusion.  The  arc  length  may  also  be  gaged  by  the  arc  voltage, 
which  can  be  measured  by  connecting  the  terminals  of  a  voltmeter 
to  the  positive  and  negative  electrodes  between  which  the  arc  is 
formed.  The  voltage  for  bare  electrodes  will  range  from  15  volts 
for  small  electrodes  to  20  volts  for  the  larger  ones.  The  average 
arc  voltage  will  be  about  18  volts.  A  comparison  between  a  long 
and  short  arc  and  their  relative  effects  are  illustrated  by  Figs.  29. 
and  29-A. 

The  arc  length  for  carbon  arc  welding  can  be  varied  over  a 
wider  range,  without  bad  effects,  than  in  the  case  of  the  metallic 
arc,  although  it  is  important  that  the  arc  length  be  within  a  certain 
range  if  the  best  results  are  to  be  had. 

In  carbon  arc  welding  if  the  arc  length  is  too  short  the  weld 
will  most  likely  be  hard  because  the  carbon  from  the  electrode 
will  be  deposited  in  the  liquid  metal  in  the  weld  where  it  will  be 
absorbed.  To  prevent  this  the  arc  length  should  be  such  as  to 
permit  the  atmosphere  to  diffuse  through  the  arc  flame  and  oxidize 
the  carbon.  It  will  be  noted  that  this  is  the  opposite  to  what  is 
desired  in  metallic  arc  welding.  An  excessive  arc  length  in  carbon 
arc  welding  will  result,  however,  in  brittle  metal  in  the  weld  the 
same  as  in  the  case  of  the  metallic  arc,  although  the  range  of  arc 
length  within  which  a  soft  weld  can  be  secured  with  the  carbon 
arc  is  so  great  that  little  difficulty  should  be  experienced  in  main- 
taining the  proper  arc  length. 

The  approximate  arc  lengths  for  different  current  values  are 
given  in  the  following  table  : 

Arc  Current  Average  Arc 

in  Amperes  Length  in  Inches 

200  Y2 

300  Y4 

400  1 

500  \y4 

The  arc  length  should  not  ordinarily  vary  more  than  ^4  m- 
below  or  above  these  values. 

Arc  Stability. — If  the  vapor  of  the  arc  stream  condenses,  the 
circuit  will  be  broken  and  the  arc  will  be  extinguished.  The 
tendency  of  the  vapor  to  condense  and  the  ease  of  maintaining 
an  arc  is  governed  by  the  stabilizing  characteristics  of  the  welding 


66  ELECTRIC  ARC   WELDING 

circuit  and  upon  the  nature  of  the  arc  gases.  A  high  open  circuit 
voltage  or  series  reactance  coil  will  help  materially  to  sustain  the 
arc.  Any  condition  which  affects  the  temperature  of  the  arc 
vapor  will  affect  its  stability,  as  mentioned  elsewhere.  An  air 
draft  will  tend  to  cool  the  arc  vapor  and  make  it  difficult  to 
maintain.  On  the  other  hand  a  coating  on  the  electrode  will 
partly  exclude  the  air  and  reduce  the  difficulty  of  arc  manipu- 
lation. 

It  is  often  found  that  the  arc  is  erratic.  This  is  caused  by  many 
different  conditions,  the  more  common  of  which  are  impure  or 
non-uniform  structure  of  welding  electrodes  and  in  some  cases  the 
plate  metal,  dirt  and  oxides  on  the  surface  of  the  part  being 
welded,  moisture,  and  magnetic  influence.  The  latter  interference 


Pene-rrafion-  No  Overlap  Poor  Fusion  and  Excessive 

Overlap 

FIG.  30— Penetration  FIG.  3O-A— Overlap 

• 

can  be  overcome  by  arranging  the  work  so  that  the  welding  will 
progress  away  from  the  ground  connection. 

Arc  Penetration. — The  penetration  is  governed  almost  en- 
tirely by  the  relative  melting  points  of  the  electrode  and  the  parent 
metal,  the  arc  length,  arc  current,  and  the  speed  of  arc  travel. 
The  depth  of  the  penetration  below  the  surface  of  the  plate  will 
be  indicated  by  the  depth  of  the  arc  crater  depression ;  this  can  be 
observed  at  any  time  by  the  operator.  The  penetration  obtained 
when  the  conditions  enumerated  above  are  correct  is  shown  in 
Fig.  30.  The  effects  of  these  conditions  upon  penetration  which 
have  not  already  been  mentioned  will  be  discussed  later. 

Overlap. — An  example  of  no  overlap  is  shown  in  Fig.  30.  It 
will  be  noted  that  the  width  of  the  union  is  at  least  equal  to  the 
width  of  the  deposit.  An  example  of  extreme  overlap  is  shown 
in  Fig.  30- A ;  this  may  be  due  to  the  melting  point  of  the  electrode 
being  lower  than  that  of  the  plate,  excessive  arc  length,  insufficient 
current  or  too  great  speed  of  arc  travel.  In  this  case  it  will  be 


ELECTRIC  ARC  WELDING  PRINCIPLES  67 

noted  that  the  width  of  the  union  is  less  than  the  width  of  the 
deposit.  The  overlap  can  be  gaged  by  observation  of  the  contour 
of  the  deposit  so  that  no  difficulty  should  be  experienced  by  the 
operator  in  determining  when  the  penetration  is  sufficient  to  pre- 
vent excessive  overlap  which  results  in  unfused  zones  in  the  weld. 

Arc  Current  for  Metallic  Electrodes. — The  amount  of  cur- 
rent required  for  metallic  arc  welding  is  dependent  upon  so  many 
factors  that  only  approximate  values  can  be  given  for  different 
size  electrodes.  For  example,  the  current  required  for  proper 
fusion  will  vary  with  the-  type  of  weld,  scarf,  cleanliness  of  sur- 
face, heat  conductivity,  thermal  capacity  of  the  work  piece  which 
is  determined  by  its  shape  and  mass,  position  of  work,  manipula- 
tion of  arc,  and  welding  procedure. 

The  approximate  current  and  electrode  size  used  in  welding  of 
mild  steel  plate  of  different  thicknesses  is  given  below : 


Electrode 
Diameter, 
Fractions  of 
an  Inch 

1      ' 

ft 

Diameter  in 
Mils  or 
Thousandths 
of  an  Inch 
94 
125 
"*          156 
188 

Plate 
Thickness, 
Fractions 
of  an  inch 
y±   and  under 

i3cj  and  up 
Y%  and  up 

Current 
in 
Amperes 
50-90 
75-150 
125-175 
140-225 

There  are  a  number  of  conditions  which  the  operator  can 
observe  as  a  guide  to  indicate  when  the  current  is  correct  for 
proper  fusion,  such  as  the  depth  of  arc  crater,  deposit  contour, 
and  arc  function,  that  is,  the  smoothness  and  uniformity  with 
which  the  metal  is  expelled  from  the  end  of  the  electrode.  If  the 
current  is  low,  even  with  a  short  arc  the  penetration  will  be  in- 
sufficient, the  same  as  in  the  case  of  a  long  arc. 

A  rule,  which  will  usually  insure  sufficient  heat  for  proper 
fusion  for  bare  electrodes,  is  to  use  as  much  heat  as  each  size  elec- 
trode will  carry  without  overheating  until  the  standard  14-in. 
length  has  been  consumed.  If  this  current  or  heat  does  not  suit 
the  work  at  hand  a  larger  or  smaller  size  electrode  should  be  used 
as  the  case  requires. 

Arc  Current  for  Carbon  Electrode  Welding. — The  current 
that  can  be  used  for  carbon  arc  welding,  like  that  for  the  metallic 
arc,  varies  with  the  thermal  capacity  of  the-  part  to  be  welded. 


68  ELECTRIC  ARC   WELDING 

For  work  of  a  given  mass  the  current  for  the  carbon  arc  is 
usually  greater  than  that  employed  for  the  metallic  arc. 

A  tempered  graphite  electrode  is  preferable  to  the  plain  hard 
carbon  electrode  as  originally  used,  because  of  its  greater  current 
carrying  capacity  and  lower  rate  of  consumption.  Its  use  also 
decreases  the  difficulty  of  securing  a  soft  weld. 

The  relation  of  current  to  electrode  diameter  in  carbon  arc 
welding  is  comparable  to  the  relation  of  gas  consumption  to  tip 
size  in  oxy-acetylene  welding,  i.e.,  a  given  size  electrode  and  cur- 
rent value  can  be  used  on  work  varying  considerably  in  thermal 
capacity.  To  obtain  economy  in  time  and  heat  energy,  however, 
an  electrode  and  current  best  suited  for  the  work  should  be  used. 

The  size  electrode  for  different  current  values  in  most  common 
use  are  given  below  for  graphite  rods : 

Current  in  Diameter 

Amperes  Inches 

100  A 

200  3/s 

300  §£ 

400  M 

500  ft 

600  1 

To  reduce  the  difficulty  of  arc  control  all  electrodes  should  be 
pointed  or  tapered  to  l/%  in.  at  the  arc  end.  The  filler  metal 
should  be  American  ingot  iron  or  extra  soft  steel.  The  usual 
oxy-acetylene  welding  rods  and  sizes — J^  in.  to  ^  in.,  depending 
on  current  used,  are  satisfactory. 


V 
TRAINING  OPERATORS  FOR  ARC  WELDING 

Before  electric  arc  welding  of  any  kind  can  be  done  by  a  begin- 
ner there  are  a  number  of  fundamental  principles  concerning  the 
art  which  must  be  learned  and  also  a  certain  knack  of  arc  manipu- 
lation which  must  be  acquired.  The  fundamental  principles  can 
be  obtained  through  study,  or  from  a  competent  instructor,  but 
the  knack  of  arc  manipulation  can  be  acquired  only  by  practice. 

Classification  of  Electric  Arc  Welding  Operators. — Electric 
arc  welding  has  developed  many  classes  of  operators  and  the  ques- 
tion has  been  asked,  "Who  is  a  skilled  operator?"  In  our  ex- 
perience we  have  found  that  operators  are  divided  into  two  gen- 
eral classes.  These  are,  universal  operators  and  specialized  oper- 
ators. The  first  class  stands  by  itself  as  its  name  indicates.  It  is 
not  subdivided  as  is  the  case  of  the  second  class.  Universal 
operators  include  those  who  are  able  to  apply  electric  arc  welding 
to  all  classes  of  work  and  kinds  of  materials  to  which  the  process 
is  adapted.  Their  skill  has  been  gained  through  broad  mechanical 
experience  and  diligent  study  of  mechanical  principles,  together 
with  extended  study  and  experience  in  arc  welding.  Those  men 
who  have  become  universal  operators  are  high-class  artisans  and 
will  be  much  in  demand  in  many  industries. 

The  specialized  operators  may  be  subdivided  into  several 
classes.  Some  are  highly  skilled  while  others  do  not  require  as 
high  a  degree  of  skill  because  of  the  class  of  work  they  perform. 
At  the  present  time  specialized  operators  may  be  classified  as 
follows:  First,  pressure  vessel  welding — (a),  high  pressure — (b), 
low  pressure ;  second,  machinery  welding,  much  of  which  is  alloy 
steel  requiring  some  knowledge  as  to  the  influence  of  heat  on 
steel  of  various  compositions;  third,  structural  welding;  fourth, 
repeat  operations,  which  requires  the  least  experience. 

From  the  foregoing  it  is  apparent  that  the  degree  of  skill  re- 

69 


70  ELECTRIC  ARC   WELDING 

quired  in  the  different  classes,  one  from  the  other,  varies  consid- 
erably ;  for  instance,  an  operator  whose  training  has  been  limited 
to  repeat  operations  would  not  be  competent  to  do  pressure  vessel 
welding,  which  not  only  requires  first-class  work  but  also  a  knowl- 
edge of  the  particular  service  the  vessel  is  to  perform  including 
a  knowledge  of  the  effect  of  expansion  and  contraction. 

The  selection  of  men  who  are  to  become  electric  welding  oper- 
ators must  be  given  careful  consideration.  In  many  cases  oper- 
ators work  under  foremen  who  know  little  or  nothing  of  the  art 
and  who  are  therefore  unable  to  judge  whether  or  not  a  weld  is 
being  made  in  the  proper  manner. 

The  quality  of  a  weld  can  be  predicted  only  through  observation 
by  one  who  is  familiar  with  the  process,  and  preferably  as.  the 
weld  progresses.  In  view  of  this  fact  it  is  obvious  that  unless  the 
operator  is  of  the  conscientious  type  and  a  firm  believer  in  quality 
work,  the  degree  of  success  will  be  very  uncertain.  The  material 
upon  which  an  operator  works  is  always  in  plain  view.  If  his 
training  has  been  ample  (as  it  should  be  before  he  undertakes  to 
make  important  welds)  and  if  ordinary  judgment  is  exercised, 
there  should  be  little  excuse  for  the  failure  of  the  weld.  Con- 
scientiousness on  the  part  of  the  operator  is  one  of  the  most  im- 
portant qualifications  necessary  for  successful  welding.  Next  in 
importance  is  mechanical  ability.  It  has  been  our  experience  that 
men  who  have  had  mechanical  training,  and  especially  those  who 
are  willing  to  disregard  any  delusion  concerning  the  process, 
make  the  most  competent  operators. 

Starting  the  Student  Welder. — Assuming  that  the  proper 
equipment,  accessories  and  electrode  material  have  been  provided, 
the  first  step  in  instructing  the  beginner  will  be  to  teach  him  to 
become  familiar  with  the  starting  of  the  equipment,  and  the  mak- 
ing of  adjustments  in  order  to  obtain  the  proper  heat  for  different 
sizes  and  kinds  of  electrodes  for  work  of  various  composition  and 
mass.  For  this  purpose  brief  instructions  attached  to  the  control 
panel  of  the  equipment  will  serve  best,  especially  when  different 
operators  use  the  same  equipment.  Instructions  of  the  character 
mentione'd  are  shown  in  Fig.  31  for  an  individual  type  of  equip- 
ment. 

The  next  step  will  be  to  teach  the  beginner  to  make  electrical 


TRAINING  OPERATORS 


71 


MOTOR  PANEL 


GENERATOR  PANEL 


To  Start  Motor : — Switch  No.  3  on  generator  panel  must  be  open. 
Close  switch  No.  I  on  motor  panel.  Advance  slowly  handle  of 
starting  box  No.  2  until  lever  is  held  in  place  by  automatic  re- 
lease magnet.  Motor  will  start  slowly,  speeding  up  as  handle  is 
advanced.  In  case  of  portable  welder,  insert  power  plug  No.  8 
having  switch  No.  I  open  before  starting  motor. 

To  Operate  Generator : — Close  double  throw  switch  No.  3  on  gen- 
erator panel  to  negative  or  positive  side  depending  on  character 
of  work.  Always  use  electrode  negative  except  when  welding 
very  thin  plates. 

Heat  Adjustment: — For  3/32-in.  or  smaller  electrodes  close 
switch  No.  4  and  adjust  voltage  by  rheostat  No.  5  to  obtain 
proper  heat  according  to  the  work  at  hand.  For  ^-in.  electrodes 
open  point  a  of  switch  No.  4  which  will  provide  the  approximate 
heat  for  this  size  of  wire.  If  heat  is  not  correct  raise  generator 
voltage  to  increase  heat  or  lower  generator  voltage  to  decrease 
heat  as  occasion  requires.  For  5/32-in.  electrodes  disengage 
point  b  and  for  3/i6-in.  electrodes  disengage  point  c,  proceeding 
for  closer  heat  adjustments  as  explained  above.  Switch  all  the' 
way  out  provides  maximum  heat  obtainable. 

When  not  welding  or  making  adjustments  on  panel,  open  main 
generator  switch  No.  3.  This  will  avoid  accidental  short-circuit. 

To  Stop  Motor: — Open  generator  switch  No.  3;  open  motor 
switch  No.  i;  starting  lever  of  box  No.  2  releases  automatically. 


FIG.  31 — Instructions  for  Starting  and  Stopping  Individual  Type 
Equipment 

connections  from  the  equipment  or  panel  to  the  part  on  which 
welding  is  to  be  done.  Assuming  that  a  bare  metallic  electrode  is 
to  be  used,  and  that  direct  current  is  provided  for  welding,  the 
positive  lead  will  be  connected  to  the  work  and  the  negative  to  the 


72 


ELECTRIC  ARC   WELDING 


electrode  holder,  as  shown  by  Fig.  32.  This  scheme  of  connec- 
tions will  concentrate  the  greater  portion  of  the  arc's  heat  on  that 
part  which  has  the  greatest  mass  and  ability  to  conduct  the  heat 
away  from  the  point  where  the  arc  is  established. 

To  furnish  protection  from  the  glare  of  the  arc  a  face  shield, 
fitted  with  glass  of  the  proper  depth  of  color  tint,  as  pointed  out  in 
another  part  of  this  book,  should  be  selected.  Until  an  operator 
has  had  sufficient  experience  to  choose  glasses  suited  best  to  his 


Electrode 
Holder 


Flexible  Cable 


Arc 


Arc 'Crater 


•f  Denotes  Positive 
~~  Denotes  Negative 
->  Arrows  Indicate  Direction 
of  Current  Flow 


Flexible  Cable 


FIG.  32 — Diagram  for  Beginner's  Use  Showing  How  Connections  Should 

be  Made 

eyes,  it  is  safe  to  begin  with  glasses  having  a  depth  of  color  tint 
such  that  when  the  light  of  the  sky  is  observed  through  them,  two 
to  five  seconds  will  be  required  for  visibility.  A  rule  which  must 
be  observed  is  to  always  have  the  face  shield  in  position  before  the 
arc  is  struck,  as  it  requires  only  a  few  flashes  to  produce  bad 
effects  on  the  eyes. 

An  electrode  of  a  given  size  should  be  chosen  according  to  the 
mass  and  nature  of  the  work.  For  practice,  a  %  in.  plate,  ap- 
proximately 1  ft.  square,  will  be  found  convenient  and  a  5/32  in. 
diameter  electrode  14  in.  or  16  in.  long  will  be  the  most  appro- 
priate size  to  use  for  work  of  this  dimension.  The  holder  should 
clamp  the  electrode  midway  between  the  two  ends,  especially  for 


TRAINING  OPERATORS 


73 


a  beginner,  as  the  shorter  distance  from  the  work  to  the  holder 
will  require  less  effort  to  hold  a  steady  arc. 

The  electrode  holder  should  be  held  in  one  hand  only  and  to 
avoid  nervousness  the  hand  should  not  grip  the  holder.  If  the 
handle  is  held  tight  the  hand  will  shake  and  increase  the  difficulty 
of  arc  control.  The  problem  is  to  acquire  absolute  control  of  the 
arm  and  hand  manipulating  the  arc  and  this  is  best  done  by 
steadying  the  body  either  by  taking  a  sitting  position,  or  if  con- 
ditions require  welding  in  a  standing  position  the  knee,  hip,  or 
shoulder  may  be  rested  against  something  to  brace  and  steadv  the 
body.  This  will  leave  the  arm  free  to  manipulate  the  arc  and 


Relative  Position  of  Electrode 
to  Work  When  Striking  Jn  Arc 


Relative  Position 
a  f  Electrode, 
/Ire  Established 


FIG.  33 — Methods  of  Striking  an  Arc 

avoid  body  movements  which  will  be  communicated  to  the  arc  and 
add  to  the  difficulty  of  arc  control.  When  in  a  sitting  position,  if 
the  holder  is  held  by  the  right  hand  the  left  elbow  may  be  rested 
on  the  left  knee,  which  will  further  reduce  the  effort  required  to 
manipulate  and  control  the  arc. 

With  the  electrode  at  approximately  right  angles  to  the  plate 
(since  the  arc  tends  to  establish  itself  along  a  straight  line  to  the 
work),  touch  the  electrode  on  the  plate  with  a  slightly  dragging 
touch,  or  by  a  sharp  turn  of  the  wrist  describing  the  arc  of  a  circle, 
and  immediately  withdraw  it  approximately  ^  in.  from  the  plate. 
This  procedure  is  shown  in  Fig.  33. 

At  this  stage  the  beginner  will  encounter  his  first  difficulty, 
because  of  the  freezing  or  sticking  of  the  electrode  or  being  unable 
to  establish  the  arc.  The  first  trouble  is  caused  by  too  much  delay 
in  withdrawing  the  electrode  from  the  plate,  and  the  latter  to 
separating  the  electrode  too  great  a  distance  from  the  plate.  By 


74  ELECTRIC  ARC   WELDING 

calmly  touching  the  electrode  to  the  plate  with  a  slightly  dragging 
touch,  after  a  few  trials  little  difficulty  will  be  experienced. 

The  use  of  coated  electrodes  greatly  reduces  the  difficulty  of 
establishing  and  maintaining  the  arc  and  will  greatly  assist  the 
beginner  in  acquiring  the  knack  of  starting  the  arc,  as  well  as  in  its 
manipulation.  If  the  hand  of  the  student  is  guided  by  an  experi- 
enced operator  for^  the  first  few  trials,  so  that  he  will  become 
familiar  writh  the  feel  and  sound  of  the  proper  welding  arc  and 
the  appearance  of  the  deposit,  the  knack  of  arc  manipulation  will 
be  more  readily  acquired. 

If  the  electrode  is  moved  at  a  uniform  speed  and  at  the  same 
time  is  fed  towards  the  plate  at  the  same  rate  of  speed  at  which 
it  is  consumed  or  deposited  (maintaining  approximately  the  Ms, in. 
space  between  the  electrode  and  work),  the  metal  should  flow 
uniformly.  If  the  flow  of  metal  is  not  uniform  when  the  arc 
length  is  correct,  the  trouble  is  usually  due  to  one  of  the  following- 
causes  :  Improper  heat,  improper  polarity,  poor  electrode  ma- 
terial, or  dirt  and  oxides  on  the  surface  of  the  work. 

The  inability  of  the  student  welder  to  judge  when  the  arc  cur- 
rent is  correct  is  usually  the  cause  of  a  nonuniform  flow  of  the 
metal  when  all  other  conditions  are  proper.  If  the  current  or  heat 
value  is  too  low,  it  will  be  difficult  to  maintain  the  arc.  The  arc 
crater  will  be  very  shallow,  indicating  poor  penetration  and  the 
deposit  will  be  light  and  very  narrow.  If  the  heat  value  is  too 
great  the  electrode  will  melt  rapidly;  the  arc  will  bite  deep  into 
the  work,  producing  a  hissing  sound  and  the  deposited  metal  will 
tend  to  boil  and  will  have  a  porous  appearance;  the  excessive 
current  will  also  cause  the  electrode  to  become  red  hot  or  hotter 
at  a  distance  of  l/2  in.  or  more  from  the  end,  after  4  in.  to  6  in. 
have  been  consumed.  When  the  electrode  approaches  a  white 
heat  the  metal  will  no  longer  deposit. 

The  heat  is  correct  when  with  the  proper  arc  length  the  metal 
flows  smoothly  and  produces  an  arc  crater  about  1/16  in.  deep, 
indicating  proper  penetration,  and  when  the  surface  of  the  metal 
shows  no  signs  of  porosity,  indicating  that  the  deposit  has  not 
been  overheated.  Under  most  conditions  where  a  bare  electrode 
is  used  with  the  proper  heat  or  current  value  the  arc  will  produce 
a  mild  metallic  crackling  sound.  This  is  thought  to  be  due  to  the 


TRAINING  OPERATORS  75 

rapid  condensation  of  the  vapor  and  current  interruptions  by  the 
liquid  metal  of  the  arc  stream.  If  the  arc  current  is  somewhat 
above  the  normal  value,  or  if  the  electrode  is  coated,  the  arc  vapor 
and  liquid  metal  will  cool  more  slowly  and  the  crackling  sound 
will  be  less  noticeable. 

A  Test  for  Polarity. — The  polarity  may  be  tested  by  placing 
a  small  carbon  rod  in  the  holder  in  place  of  the  metallic  electrode 
and  drawing  an  arc  between  the  carbon  and  an  iron  plate.  If  the 
arc  is  difficult  to  maintain  it  is  generally  an  indication  that  the 
polarity  of  the  work  is  negative  and  the_carbon  positive;  conse- 
quently the  connections  are  reversed.  If  the  arc  is  stable  the  plate 
is  positive;  in  which  case  iron  vapor  forms  more  readily  than 
carbon  vapor,  and  the  connections  are  properly  made.  If  tests  of 
the  nature  just  described  are  made  for  the  benefit  of  the  beginner, 
and  his  attention  is  called  to  the  characteristic  features  mentioned 
above,  the  polarity  will  soon  become  apparent  to  him.  Every 
operator  should  become  familiar  with  the  test.  Some  operators 
who  have  had  considerable  experience  are  able  to  determine  the 
polarity  with  a  metallic  electrode  instead  of  a  carbon.  However, 
the  carbon  will  serve  best  for  a  beginner. 

Electrode  material  unsuitable  for  welding  will  usually  be  indi- 
cated by  an  erratic  arc  or  by  the  metal  melting  in  large  globules, 
resulting  in  a  nonuniform  flow  of  metal  and  consequently  poor 
penetration,  as  well  as  a  brittle  porous  deposit. 

Importance  of  Clean  Work  and  Proper  Arc  Length. — If  the 
surface  of  the  work  is  not  clean,  the  arc  will  play  around  and  the 
metal  will  not  flow  uniformly.  The  metal  of  the  electrode  will 
unite  uniformly  on  the  work  only  when  all  dirt,  oxide  or  any 
foreign  substances  have  been  removed.  It  is  as  impossible  to 
have  a  sound  weld  where  the  surface  is  not  clean  as  jt  is  to  heat 
and  unite  two  pieces  of  pitch  with  the  surfaces  to  be  united  cov- 
ered with  oil.  If,  however,  the  oil  is  removed  or  floated  from 
between  the  surfaces  to  be  jointed,  a  perfect  homogenous  union 
will  be  effected.  This  fact  must  not  be  lost  sight  of  in  arc  weld- 
ing if  the  best  results  are  to  be  obtained.  Poor  electrode  material 
is  sometimes  difficult  to  detect,  as  far  as  the  operator  is  concerned. 
About  the  only  way  he  has  of  determining  when  the  material  of 


76  ELECTRIC  ARC   WELDING 

the  electrode  is  causing  the  nonuniform  flow  of  metal  or  an 
unstable  arc,  is  by  knowing  that  all  other  conditions  are  correct. 

Again  referring  to  the  proper  arc  length:  while  it  is  judged 
to  be  approximately  %  in.  it  is  somewhat  difficult  to  determine 
this,  because  the  shape  of  the  arc  tends  to  obscure  the  view.  In 
practice  if  the  heat  is  correct  the  proper  arc  length  is  judged  by 
the  appearance  of  the  deposited  metal,  the  depth  of  the  arc  crater 
penetration,  extent  of  overlap  of  the  added  metal,  and  whether  or 
not  the  arc  shifts  on  the  work  piece.  Once  an  operator  becomes 
familiar  with  the  sound  of  the  arc  under  given  conditions,  his 
sense  of  hearing  will  assist  materially  in  determining  the  proper 
arc  length. 

Arc  Current  and  Voltage. — The  approximate  current  and 
voltage  for  different  electrode  sizes  for  different  plate  thicknesses 
are  given  in  the  following  table  : 

Voltage 
at 
Arc 

14-16 
15-17 
18-22 
17-20 

It  is  impossible  to  furnish  more  definite  data  as  to  the  arc 
voltage  and  current  with  relation  to  the  size  of  electrode  and  plate 
thickness,  as  many  factors  enter  into  this  determination.  For 
example,  a  %  in.  bare  mild  steel  electrode  used  on  a  3/16  in.  plate 
would  require  approximately  80  amperes.  If,  however,  the  same 
size  electrode  were  used,  for  instance,  on  a  locomotive  frame,  the 
current  which  would  be  required  to  give  proper  fusion  would 
approximate  140  amperes,  and  under  ordinary  conditions  that 
amount  of  current  would  overheat  the  electrode  by  the  time  ap- 
proximately 8  in.  were  consumed.  The  difference  in  the  current 
demand  is  due  to  the  difference  in  the  thermal  capacity  and  con- 
ductivity of  the  two  parts.  In  the  case  just  mentioned  a  larger 
electrode  would  be  more  appropriate  since  it  would  provide  carry- 
ing capacity  great  enough  for  proper  fusion  without  overheating 
until  the  ordinary  electrode  length  had  been  consumed. 

Angle  of  Electrode. — The  angle  at  which  the  electrode  is 


Electrode 
Diameter, 
Fractions 
of  an  Inch 

Plate 
Thickness, 
Fractions 
of  an  Inch 

Current 
in 

Amperes 

1      I 

^4  and  under 

y8-i/2 

&  and  up 
%  and  up 

50-90 
75-150 
125-175 
140-225 

TRAINING  OPERATORS  77 

held  with  relation  to  the  surface  on  which  metal  is  added,  as  well 
as  with  respect  to  direction  of  arc  travel,  will  influence  the  pene- 
tration and  ease  of  directing  the  metal  at  the  point  desired  in  the 
weld. 

It  is  difficult  accurately  to  give  the  proper  electrode  angles  for 
the  various  conditions.  In  general,  the  added  metal  seems  to  be 
more  easily  directed  where  desired,  for  different  positions,  if  the 
electrode  is  slightly  inclined,  approximately  20  deg.  from  a  line 
drawn  at  right  angles  from  the  face  of  the  weld.  The  electrode 
angle  with  respect  to  the  direction  of  arc  travel  will  vary  with  the 
position  of  the  work  and  other  conditions.  For  flat  welding,  the 
electrode  angle  would  be  as  shown  by  Fig.  38.  For  other  posi- 
tions, such  as  vertical  seam  welding,  the  electrode  angle  may  be 
inclined  in  an  opposite  direction  to  the  direction  of  arc  travel. 
This  will  direct  the  arc  to  the  point  where  the  metal  is  to  be  added 
and  minimize  the  change  for  poor  fusion  at  the  base  of  the 
deposit.  The  penetration  or  fusion  of  the  parent  metal  may  be 
varied  to  some  extent  by  varying  the  angle  of  the  electrode.  This 
fact  can  be  taken  advantage  of  at  times  to  reduce  the  tendency 
of  the  arc  to  burn  through  thin  edges  or  to  prevent  metal  from 
sagging  when  welding  in  positions  other  than  flat.  Care  should 
be  used  in  this  practice,  however,  for  if  the  electrode  is  inclined 
too  much,  the  penetration  will  be  insufficient. 

Practice  Exercises. — In  order  that  a  beginner  may  become 
familiar  with  holding  the  proper  arc,  good  practice  exercises  are 
suggested,  as  follows : 

First,  with  the  heat  at  the  proper  value,  deposit  a  number  of 
layers  on  a  plate  in  a  horizontal  position  (Fig.  34)  until  it  is 
possible  to  deposit  a  layer  approximately  8  in.  long  without  inter- 
ruption, which  will  be  smooth  and  uniform  in  width  and  depth. 
This  should  be  repeated  a  sufficient  number  of  times  to  check  the 
ability  of  the  operator  to  maintain  a  uniform  arc. 

Second,  mark  a  number  of  lines  on  the  plate  with  a  piece  of 
chalk,  some  straight  and  some  crooked ;  now  repeat  the  first  exer- 
cise along  the  chalk  marks  (Fig.  35).  This  test  will  demonstrate 
one's  ability  to  hold  a  uniform  arc  and  at  the  same  time  follow  a 
certain  course. 

Third,  deposit  a  pad  approximately  1  in.  wide  in  the  manner 


TRAINING  OPERATORS  79 

shown  in  Figs.  36  and  37.  At  the  end  of  a  bead,  or  layer,  where 
the  arc  is  broken,  a  bad  crater  will  tend  to  form,  but  in  order  to 
minimize  this  condition,  it  is  advisable,  when  it  is  desired  to  break 
the  arc,  to  shorten  the  length  of  the  arc  as  much  as  possible  and 
then  break  it  quickly  by  pulling  the  electrode  to  one  side. 

The  exercises  above  outlined  should  be  practiced  not  less  than 
two  days  before  work  of  any  kind  is  undertaken. 

Building-Up  Exercise. — There  is  a  vast  amount  of  building- 
up  work  done  by  means  of  the  electric  arc,  using  either  the  carbon 
or  the  metallic  electrodes.  Materials  of  almost  every  description 
are  reclaimed  by  this  method,  and  in  many  cases  parts  that  have 
been  built-up  must  afterwards  be  machined.  When  this  is  neces- 
sary the  metallic  electrode  is  generally  employed,  but  the  carbon 
electrode  may  be  used,  in  which  case,  however,  considerably  more 
skill  is  required  to  produce  a  soft  weld.  The  weld  must  also  be 
sound.  It  must  be  free  from  slag  inclusions,  air  pockets,  etc.,  in 
order  to  give  a  smooth  finish.  When  the  metallic  electrode  is 
used  the  weld  will  be  soft  if  the  proper  heat  is  provided  as  out- 
lined above  with  a  short  arc  and  the  work  is  kept  clean. 

A  practice  exercise,  which  will  serve  to  train  an  operator  for 
this  class  of  work  is  as  follows :  Deposit  pads  of  metal  such  as 
illustrated  in  Figs.  36,  37  and  38;  these  show  the  course  the  elec- 
trode should  follow.  Additional  layers  must  overlap  the  preced- 
ing ones,  as  shown  by  Fig.  37.  When  a  pad  approximately  6  in. 
long  has  been  deposited,  clean  the  surface  perfectly  with  a  chisel 
or  roughing  tool  to  loosen  the  scale,  and  a  wire  brush  to  remove  it, 
or  by  the  use  of  a  sand  blast ;  then  proceed  to  deposit  a  second  pad, 
following  closely  the  course  of  the  first.  At  least  three  layers 
should  be  applied  in  this  manner.  The  finished  weld  should  then 
be  cut  diagonally,  and  the  ends  ground  and  polished.  By  this 
means  the  soundness  or  appearance  of  the  added  metal  may  be 
observed.  The  necessity  of  cleanliness  will  be  appreciated  by 
repeating  the  above  exercise  without  cleaning  between  layers  and 
comparing  the  cross-sections. 

The  same  exercises  as  outlined  with  the  work  in  a  horizontal 
position  should  now  be  practiced  with  the  plate  in  a  vertical  posi- 
tion until  vertical  welding  is  no  more  difficult  for  the  student  than 
down-hand  or  flat  welding.  When  the  practice  exercises,  as 


80 


ELECTRIC  ARC   WELDING 


heretofore  outlined,  have  been  perfected  to  a  fair  degree,  the 
student  should  be  allowed  to  do  unimportant  commercial  welding 
for  two  weeks  or  more  before  attempting  overhead  welding, 
which  is  exceedingly  difficult,  at  least  until  the  operator  has  mas- 
tered the  art  of  arc  manipulation  and  is  able  to  judge  when  the 
heat  value  is  proper  by  the  behavior  of  the  arc  and  the  appear- 
ance of  the  metal.  These  things  he  can  learn  only  by  experience. 


Course  of 
Electrode 


FIG.40. 
Flat  or  Down  Position  Seams. 


.Course  of 
Electrode 


FIG.  41. 
Vertical  Seams. 


_.  Course  of 
Electrode 


FIG.  4-2. 

Honzorvfal  Seams.  P|r    . 

A-Shows  course  of  Electrode  for  ~       V      T,  ^ 

finishing  with  one  layer.  Overhead  Seams. 

B-  With  more  than  one  layer. 

FIGS.  40  to  43 — Adding  Metal  to  Joints,  Showing  Course  of  Electrode  and 
Method  of  Building  up  Metal 


Practice  exercises  similar  to  those  outlined  for  the  other  positions 
will  suffice  for  overhead  welding. 

Course  of  Electrode. — When  parts  are  joined  by  welding, 
the  joint  is  usually  arranged  to  form  a  V-shaped  opening  into 
which  metal  is  fused  to  effect  the  union.  The  V  may  be  formed 
by  beveling  the  edges  that  form  the  joint  or  seam;  or,  the  position 
of  one  part  with  respect  to  the  other  may  be  such  as  to  form  a  V 
without  beveling.  The  manner  in  which  the  metal  is  fused  in  an 
opening  so  formed,  will  determine  to  some  extent,  the  strength 
and  quality  of  the  weld. 


TRAINING  OPERATORS  81 

Experience  has  shown  that  a  stronger  joint  is  obtained  when 
the  course  of  the  electrode  is  back  and  forth  across  the  V  to  be 
filled  in,  or  zvhen  the  deposit  is  parallel  with  the  line  of  stress. 
The  course  of  the  electrode,  to  allow  this  procedure  for  joints  or 
seams  in  the  different  positions,  is  shown  by  Figs.  40  to  43. 

Procedure. — When  depositing  the  first  layer  between  abut- 
ting plate  edges  or  member  ends,  care  must  be  exercised  to  secure 
fusion  completely  through  to  the  bottom  of  the  V ;  when  possible 
an  inspection  should  be  made  to  see  that  the  first  deposit  projects 
through  slightly  on  the  reverse  side. 

Additional  layers  should  be  fused  to  the  preceding  layers  and 
the  scarfed  edges.  The  weld  for  plates  and  shapes  should  be  fin- 
ished with  a  slight  welt  1/16  in.  to  J/£  in.  above  the  plate  sur- 
face. Heavy  members  should  be  given  a  greater  reinforcement, 
depending  on  the  service  requirements  of  the  part. 

Where  plate  edges  are  welded  from  one  side  only  (when  condi- 
tions permit)  a  more  efficient  weld  can  be  made  if  the  metal  pro- 
jecting through  on  the  reverse  side  is  chipped  away  and  a  light 
layer  applied,  finishing  the  weld  with  a  slight  welt  on  both  sides 
of  the  joint. 

Vertical  seam  welds  are  started  as  shown  by  Fig.  41.  When 
the  opening  at  the  bottom  of  the  V  is  bridged  by  a  slight  deposit, 
a  shoulder  is  formed  which  provides  an  almost  horizontal  surface, 
upon  which  additional  metal  is  deposited  without  great  difficulty. 
To  facilitate  access  for  fusion  along  the  beveled  edges,  the  deposit 
at  the  bottom  of  the  V  should  be  kept  in  advance  of  the  back  or 
outer  edge  of  the  fused-in  metal,  to  form  a  declining  surface. 

Horizontal  seam  welds  are  started  by  fusing  together  the  edges 
at  the  bottom  of  the  V  with  a  slight  deposit.  The  fused-in  metal 
on  the  bottom  beveled  edge  is  then  kept  in  advance  of  that  of  the 
top  beveled  edge,  as  shown  by  Fig.  42.  Overhead  seam  welds  are 
made  by  starting  at  the  apex  of  the  V  and  forming  a  shoulder 
with  an  initial  deposit  extending  down  between  the  beveled  edges. 
A  vertical  surface  is  thus  formed  and  additional  metal  is  then 
added  between  it  and  the  beveled  edges  of  the  plates— the  groove 
usually  present  on  the  top  side,  due  to  sagging' of  the  metal  be- 
tween the  edges  of  the  plate,  is  a  common  weakness  of  overhead 
welds.  Operators  who  have  had  considerable  experience  on  over- 


82  ELECTRIC  ARC   WELDING 

head  welding  can  eliminate  this  by  slightly  projecting  the  end  of 
the  electrode  through  the  opening  between  the  thin  edges  when 
making  the  initial  layer.  It  may  also  be  prevented  by  placing  thin 
strips  on  the  top  or  reverse  side  from  where  the  welding  is  done. 
These  may  be  cut  in  short  lengths  6  in.  to  10  in.  long.  By  sticking 
an  electrode  to  them  to  serve  as  a  handle,  they  can  then  be  passed 
through  the  opening  edgewise  and  placed  and  held  in  position.  If 
conditions  permit,  when  the  weld  is  completed  the  strips  should  be 
chipped  off. 

Effect  of  Layer  Sequence  on  Weld  Strength. — For  some 
time  it  has  been  known  that  the  strength  of  a  weld  is  greatest 
when  the  stress  is  applied  parallel  with  the  direction  of  the  deposit. 
It  is  for  this  reason  that  joints  are  most  always  formed  by  tiers 
of  parallel  layers  across  the  V-shaped  opening,  rather  than  par- 
allel with  the  joint;  or  when  building  up  a  shaft  the  layers  are 
usually  made  parallel  with  the  shaft. 

Recently  tests  have  been  conducted  more  accurately  to  deter- 
mine the  strength  of  the  metal  according  to  the  direction  of  the 
stress  with  respect  to  the  direction  of  the  deposit.  The  following 
is  taken  from  an  article  in  the  February  15  issue  of  Power,  by 
O.  H.  Eschholz,  research  engineer,  Westinghouse  Electric  & 
Manufacturing  Co. : 

The  process  of  metallic  electrode  arc  welding  requires  fusion 
between  the  members  of  a  joint  and  an  intermediate  casting.  It  is 
evident  that  the  weld  properties  are  determined  by  the  character- 
istics of  (1)  the  original  or  parent  metal,  (2)  the  metal  adjacent 
to  zone  of  fusion,  altered  by  thermal  cycle,  and  (3)  the  arc-de- 
posited metal.  Metal  deposition  is  accomplished  by  transferring 
small  liquid  globules  from  a  wire  electrode  to  a  crater  formed  by 
the  arc  in  the  parent  metal.  By  controlling  the  direction  of  the 
arc  travel,  a  sequence  of  such  globules  may  be  fused  in  layer 
form  to  the  surface  of  the  scarfed  joint  or  previously  deposited 
metal.  In  order  to  build  up  a  surface  or  completely  fill  a  section, 
tiers  of  such  parallel  layers  may  be  deposited  in  some  predeter- 
mined sequence. 

It  is  evident  that  the  completed  deposit  consists  of  an  aggregate 
of  fused  globules.  For  every  pound  of  metal  cast  when  using  a 
bare,  low-carbon  steel  electrode,  5/32  in.  in  diameter  and  150- 


TRAINING  OPERATORS  83 

ampere  arc  current,  it  is  estimated  that  roughly  30,000  globules 
are  transferred.  These  attain  a  temperature  of  about  2,000  deg. 
C.  at  the  wire  electrode  arc  terminal,  then  pass  across  the  arc 
stream,  subject  to  more  or  less  attack  by  enveloping  gases,  to  be 
deposited  finally  on  a  surface  previously  liquefied  by  the  energy 
developed  at  the  positive  arc  crater.  Owing  to  the  relatively  high 
thermal  capacity  of  the  joint  members  the  deposited  metal  is 
cooled  at  a  very  rapid  rate,  analogous  to  that  of  quenching.  The 
effect  of  superposing  deposits  is  to  partly  anneal  preceding 
quenched  deposits.  It  is  evident  that  metal  so  formed  may  possess 
properties  differing  from  those  of  steel  cast  in  large  masses,  sub- 
jected to  mechanical  working,  and  then  a  prescribed  heat  treat- 
ment. It  is  also  conceivable  that  changes  in  arc-metal  properties 
may  be  achieved  by  modifying  arc  and  electrode  manipulation, 
electrode  constituents,  arc  gases  and  circuit  characteristics.  The 
evaluation  of  these  factors  may  be  expedited  by  confining  test 
observations  to  the  properties  of  the  deposited  metal,  thereby 
eliminating  the  many  variables  introduced  by  the  characteristics 
of  the  shank  metal,  type  of  joint  and  the  character  of  fusion  that 
exists  between  the  deposited  and  the  original  plate  metals  being 
welded. 

The  preferred  method  for  building  up  a  surface  or  filling  in  a 
joint  is  to  deposit  the  arc  metal  in  layers  and  tiers.  The  fusion 
patterns  obtained  between  adjacent  layers  are  clearly  shown  in 
Fig.  43- A. "3, 

It  will  be  noted  that  if  load  is  applied  in  the  direction  of  A., 
Fig.  43-A,  or  in  line  with  the  direction  of  deposition,  the  fused 
zones  are  stressed  in  parallel.  However,  if  load  is  applied  in  the 
direction  B,  or  transverse  to  the  direction  of  deposition,  the 
zones  of  adjacent  layer  fusion  are  stressed  in  series.  If  the  load 
is  applied  along  C,  or  axially,  the  zones  of  fusion  of  superposed 
layers  are  stressed  in  series.  To  determine  the  relation  between 
stress  and  direction,  metal  was  deposited  on  a  plate  j/^-in.  thick, 
using  a  5/32-in.  mild-steel  electrode,  175  amperes  short  arc  length, 
and  the  surface  of  each  layer  was  cleaned  before  forming  the  next 
layer.  After  normalizing  each  sample,  by  holding  at  1,650  deg.  F. 
for  15  min.  and  cooling  in  air,  the  base  plate  was  removed  and  the 
following  test  pieces  cut:  (1)  Standard  A.  S.  T.  M.  2-in.  gage 


84 


ELECTRIC  ARC   WELDING 


length,  0.505-in.  diameter  tensile-test  specimen;  (2)  2l/2  in.  long, 
0.798-in.  diameter  compression  column;  (3)  y^  in.  x^x9-in. 
bending,  transverse  and  cantilever  test  specimens ;  (4)  one  centi- 
meter square  notched  Izod  Impact  test  specimen. 

In  Table  I  are  given  the  properties  of  arc-deposited  metal  with 
reference  to  the  direction  of  deposition.  An  inspection  of  this 
table  shows  that  the  best  results  are  obtained  when  depositing  the 
metal  in  the  direction  of  stress.  The  greatest  variation  in  prop- 


A-A — In    line    with    direction    of    deposit,    fused    zones,     stressed    in    parallel,     giving 

maximum   strength. 
B-B — Transverse    to    direction    of    deposit;   the    zones    of    adjacent     layers    fused    are 

stressed  in  series. 
C-C — Direction   of   stress  axially.      Here   the  number  of  fused   zones  of  super-imposed 

layers  are  stressed  in  series. 

erties  is  secured  when  subjecting  the  material  of  the  various  speci- 
mens to  a  tension  stress.  When  the  direction  of  stress  is  parallel 
to  the  direction  of  deposition,  the  number  of  fused  zones  stressed 
in  series  is  a  minimum,  while  when  the  direction  of  stress  is 
axially,  as  in  C,  the  number  of  fused  zones  in  series,  as  well  as 
slag  pockets,  is  a  maximum.  It  is  interesting  to  note  that  the 
results  for  sample  B,  which  represents  the  condition  existing  in 
most  welding,  is  intermediate  between  A  and  C.  These  data  sug- 
gest that  the  metal  deposited  should  be  formed  in  a  direction  so 
that  the  greatest  stress  will  be  parallel  to  the  direction  of  deposi- 
tion. When  this  is  not  possible,  the  number  of  layers  in  series, 
case  B,  may  be  reduced  by  widening  the  deposit.  Since  these 
observations  represent  the  limitations  of  the  operator  as  well  as 


TRAINING  OPERATORS 


85 


TABLE  I.     PROPERTIES  OF  ARC-DEPOSITED  METAL. 


Metal  Constituents:  C. 

Analysis  of  wire  electrode,  per  cent 0.16 

Analysis  of  deposited  metal,  per  cent 0.05 

Tensile : 

/ — Pounds  per  Square  Inch — \ 

Deposit  Yield  Elastic 

Fig.  43- A  U.T.S.  Point          Limit 


Mn 
0.56 
0.19 


S 

0.024 
0.013 


P  Fe 
0.032  99.2 
0.024  99.7 


Per  Cent   Per  Cent 
Elongation     Red. 
in  2  In.    of  Area 


A    56,100  33,400  27,500  18.1  30.8 

56,075  35,875  29,000  16.0  23.4 

58,225            18.0  27.8 

B    51,375  29,050  24,000  14.1  18.8 

C    40,875  29,400  24,250  4.4  15.9 

43,500  28,900  20,000  4.9  7.0 

Load  at  10  Per  Cent  Elastic  Limit 

Compression  :  Compression  Lb.  per  Sq.  In.  Lb.  per  Sq.  In. 

A    63,250  32,000 

B    60,750  30,700 

C    60,700  30,400 

Ultimate  Stress 
Cantilever :  Lb.  per  Sq.  In.,  6-In.  Arm. 

A    64,600 

B 63,400 

C    61,000 

Elastic  Limit,  Lb. 

per  Sq.  In. 
Transverse  :  (6  In.  between  Supports) 

A    27,850 

B    28,000 

C    28,500 

Stress  at  Shear, 
Shear :  Lb.  per  Sq.  In. 

A    39,200 

B    41,450 

C    38,500 

Foot-Lb.  to  Fracture  Standard  Notched  Specimen 
Impact,  Izod :  Test  No.  1        Test  No.  2        Test  No.  3 

A    1.5  1.5  1.5 

B    1.5  1.0  1.5 

C  1.0  1.5  1.5 

Distance    in    Inches    Be- 
tween Inner  Edges  of 
U  at  Fracture,  at  Points 
Bending:  1  jn.  from  Weld. 

A    0.625 

B   1.00 

C 1.25 

Hardness:  Brinell,  No.  114. 


86  ELECTRIC  ARC   WELDING 

those  of  the  process,  improvement  in  either  will  tend  to  better  the 
properties  of  metal  formed  in  sample  B  and  C. 

In  the  building  up  of  heavy  sections  it  is  usual  practice  to 
deposit  alternate  tiers  at  right  angles.  It  is  evident  that  this 
method  should  give  results  intermediate  between  those  obtained 
with  A  and  B.  The  characteristics  of  a  14-lb.  deposit  built  up  in 
such  a  manner  are  given  in  Table  II. 

TABLE  II.     PROPERTIES  OF  ARC-DEPOSITED  METAL  WHEN  LAYERS  OR  SUPER- 
POSED TIERS  ARE  DEPOSITED  AT  RIGHT  ANGLES. 

/ Pounds  per  Square  Inch \  Per  Cent  Per  Cent 

Yield  Elastic  Elongation  Reduction 

U.T.S.  Point  Limit  in  2  In.  of   Area 

58,825  41,000  34,500  9.2  19.9 

54,650  35,000  29,000  6.5  13.4 

Compression :     Elastic  Limit,  Ib.  per  sq.  in.,  29,450  and  34,500. 

Hardness,  Brinell,  No.  114. 

Shear:    46,200  and  44,600  Ib.  per  sq.  in. 

Bending :     100  deg.  on  1  in.  radius,  bar  y?.  in.  thick. 

Impact  Izod :  Unannealed  specimens  2.2  and  1  foot  pounds. 

While  experience  has  shown  that  layer  deposition  partly  anneals 
the  weld,  facilitates  slag  flotation  and  reduces  slag  pockets,  there 
are  still  many  operators  who  completely  fill  the  section  between 
joint  surfaces  as  they  progress  along  the  seam  without  regard  to 

TABLE  III.  TENSILE  PROPERTIES  OF  ARC  METAL  FORMED  BY  BULK  DEPOSITION. 

' Pounds  per  Square  Inch \  Per  Cent  Per  Cent 

Yield  Elastic  Elongation  Reduction 

U.T.S.  Point  Limit  in  2  In.  of   Area 

35,375  22,500  19,000  3.6  10.8 

31,875  22,000  20,000  3.2  9.3 

Ratio  of  average  results  obtained  from  bulk  deposition  to  Average  Re- 
sults, A  and  B,  Table  I  and  Table  II,  from  layer  deposition,  per  cent: 
60  64  65  24  45 

the  form  of  the  deposit.  This  procedure  may  be  termed  bulk 
deposition.  The  test  results  from  a  number  of  deposits  formed  in 
this  manner  are  given  in  Table  III. 

This  comparison  shows  clearly  that  a  marked  reduction  in 
strength  and  ductility  occurs  when  the  arc  metal  is  deposited  in 
bulk  rather  than  in  layer  form.  It  is  evident  that  difference  in 
procedure  in  the  deposition  of  arc  metal  may  easily  account  -for 


TRAINING  OPERATORS  87 

the  differences  in  results  obtained  in  both  commercial  and  experi- 
mental welding. 

Characteristics  of  Electrode  Materials. — Until  recently  iron 
or  mild  steel  were  about  the  only  grades  of  welding  material  com- 
mercially used  for  metallic  arc  welding.  With  the  growth  of  the 
welding  industry,  however,  the  demand  for  welding  materials  of 
various  compositions  of  both  ferrous  and  non-ferrous  metals  has 
after  considerable  research  and  development  resulted  in  a  number 
of  different  materials  being  placed  on  the  market  until  at  present 
there  are  available  ingot  iron,  mild  steel,  medium  carbon  steel, 
high  carbon  steel,  high  manganese  steel,  vanadium  and  nickel 
steels.  Some  of  these  materials  have  been  used  extensively,  while 
others  have  been  used  only  to  a  very  limited  extent,  especially  the 
alloy  steels,  due  largely  to  the  fact  that  many  of  the  alloy  steels 
require  subsequent  heat  treatment  to  secure  the  maximum  ad- 
vantage. 

The  globular  formation  at  the  electrode  terminal  is  a  feature 
common  to  all  such  materials  when  used  for  metallic  arc  welding, 
although  conditions  required  for  their  use,  the  character  of  the 
globule  metal,  size^and  rate  of  formation  vary  greatly  with  the 
wire  analysis,  diameter,  polarity,  covering,  current  density,  arc 
length,  heat  treatment,  mechanical  structure,  character  of  parent 
metal,  etc. 

Quantitative  information  relating  to  the  characteristics  of  all 
the  materials  above  mentioned  is  not  available.  Sufficient  re- 
search has  not  as  yet  been  made  to  develop  definite  working  data, 
Reference  will  be  made  only  to  the  characteristics  so  far  observed, 
and  the  conditions  under  which  these  materials  have  been  used. 

Iron  or  Very  Low  Carbon  Content  Wire. — This  material 
naturally  has  a  high  melting  point,  and  is  very  susceptible  to  flux- 
ing agents ;  i.  e.,  the  metal  becomes  very  fluid  if  any  form  of  flux- 
ing agent  is  introduced,  as  for  example,  silica.  This  can  be  no- 
ticed when  welding  on  wrought  iron  where  the  slag  in  the  wrought 
iron  exercises  a  fluxing  action  on  the  arc-fused  metal.  Another 
characteristic  of  commercially  pure  iron,  which  it  possesses 
through  a  critical  range,  is  that  the  metal  assumes  a  pasty  form 
in  the  neighborhood  of  950  deg.  C.  This  condition  facilitates  the 
penetration  of  atmospheric  gases.  This  can  be  noticed  by  heating 


88  ELECTRIC  ARC   WELDING 

the  end  of  an  electrode  by  holding  a  long  arc,  when  the  globule 
will  expand.  On  examination,  the  globule  will  be  found  hollow. 
This  is  thought  to  be  due  to  the  formation  and  expansion  of 
carbon-oxide  gas  within  the  globule,  which  action  is  intensified 
by  the  penetration  of  the  atmospheric  gases. 

Mild  Steel. — The  characteristics  of  bare  mild  steel  and  bare 
iron  electrode  materials  are  so  closely  related  that  it  is  difficult  to 
distinguish  between  them.  The  typical  hollow  globular  formation 
formed  by  holding  a  long  arc  with  an  iron  wire  also  occurs  with 
mild  steel,  although  to  a  lesser  degree.  This  is  thought  to  be  due 
to  the  liberation  of  carbon-oxide  gas,  which  tends  to  exclude  at- 
mospheric gases.  Neither  does  the  metal  become  so  fluid  when 
subjected  to  the  action  of  a  fluxing  agent,  this  being  due  to  the 
opposition  offered  by  the  carbon  present  in  the  mild  steel  to  the 
action  of  a  fluxing  agent.  The  gas  formed  within  the  electrode 
on  heating  carbon-bearing  steel  seems  to  form  a  blast  which 
assists  the  globular  transfer  and  facilitates  vertical  or  overhead 
welding. 

The  hollow  globular  formation  referred  to  above  exists  only 
with  long  arc  welding;  welds  made  with  either  iron  or  mild  steel 
using  a  short  normal  arc  length  are  known  to  be  free  from  per- 
ceptible gas  pockets. 

Medium  Carbon  Steel. — When  welding  with  medium  car- 
bon steel  of  about  0.35  carbon,  both  coated  and  bare,  the  forma- 
tion of  carbon-oxide  gas,  and  the  blast  produced  by  the  expansion 
of  gas  within  the  electrode,  becomes  more  pronounced;  also  the 
lower  melting  point  of  the  material,  which  decreases  with  an  in- 
crease of  carbon  content,  becomes  noticeable.  This  necessitates 
the  use  of  a  higher  electrode  current  density  to  secure  adequate 
penetration.  With  this  material  a  slightly  high  arc  potential  is 
observed  and  is  thought  to  be  due  to  a  larger  globular  formation 
which  necessitates  a  slight  increase  of  the  normal  arc  length. 
When  used  bare  the  surface  tension  of  the  deposit,  where  the 
chilling  action  is  very  great,  often  develops  checks.  This  trouble 
is  greatly  minimized  where  the  wire  is  coated  and  is  no  doubt  due 
to  the  prolonged  cooling  affected  by  the  coating,  which  reduces  the 
surface  tension  of  the  deposit.  The  loss  of  carbon  in  passing  the 


TRAINING  OPERATORS  89 

metal  through  the  arc  is  greatly  reduced  where  the  wire  is  coated 
and  the  welding  characteristics  are  greatly  improved. 

High  Carbon  Steel. — This  grade  of  material  is  often  used 
for  building  up  track  parts  or  other  parts  requiring  high  resistance 
to  abrasive  wear.  The  distinctive  features  of  a  carbon  steel  wire 
of  about  1.0  per  cent  carbon  when  used  for  welding  is  the  absence 
of  the  typical  hollow  globule  even  when  a  long  arc  is  held.  The 
envelope  of  carbon-oxide  gas  around  the  arc  formed  from  the 
large  amount  of  carbon  burned  is  thought  to  exclude  the  atmos- 
phere and  prevent  the  penetration  of  atmospheric  gases.  The 
globule  is,  therefore,  free  from  oxidation  and,  unlike  those  formed 
from  iron  or  mild  steel  with  a  long  arc,  is  found  to  be  solid. 

In  welding  with  high  carbon  steel  electrode  material  it  has  been 
found  that  the  penetration  and.  arc  function  is  improved  if  the 
polarity  is  reversed,  i.  e.,  electrode  positive,  which  is  opposite  to 
that  used  for  ordinary  iron  or  mild  steel  material.  When  used 
bare  two-thirds  to  one-half  of  the  carbon  content  is  burned  out 
This  loss,  as  in  the  case  of  the  medium  carbon  steel,  is  greatly 
reduced  if  the  wire  is  coated  so  that  to  obtain  a  given  carbon 
content  in  the  weld;  the  carbon  content  of  the  wire  can  be  con- 
siderably less  when  the  wire  is  coated  than  would  be  required  if 
the  wire  were  bare.  With  this  material,  as  previously  stated,  the 
coating  improves  the  welding  characteristics  and  minimizes  the 
locked-in  strain  and  surface  tension  of  the  deposit. 

Nickel  and  Vanadium  Steels. — The  use  of  these  materials 
for  arc  welding  is  in  such  a  state  of  development  that  the  reliable 
data  available  are  not  thought  to  be  sufficient  to  warrant  comment 
at  this  time. 

High  Manganese  Steel. — Steel  containing  from  12  per  cent 
to  14  per  cent  manganese  when  used  for  welding  requires  very 
special  processing  before  using  and  a  special  method  of  applica- 
tion. Unless  protected  from  atmospheric  gases  and  cooled  quickly 
the  deposit  will  be  very  brittle  and  practically  worthless.  This  is 
due  to  two  principal  conditions: 

1.  If  the  loss  of  manganese  in  passing  through  the  arc  is  such 
as  to  reduce  the  manganese  content  of  the  deposit  to  within  the 
neighborhood  of  7  per  cent.  (Manganese  between  1>^  per  cent 
and  ST/2  per  cent  in  steel  causes  brittleness.) 


90  ELECTRIC  ARC   WELDING 

2.  If  the  metal  is  cooled  slowly  the  deposit  will  be  very  porous 
and  brittle.  This  is  because  manganese  steel  is  opposite  in  this 
respect  to  carbon  steel ;  i.  e.,  quick  cooling  makes  the  metal  ductile 
while  slow  cooling  makes  it  very  hard  and  brittle.  The  bad  effect 
caused  by  the  atmosphere  is  eliminated  by  the  use  of  a  special 
coating  which  serves  to  confine  the  arc  gases  and  limit  the  pene- 
tration of  atmospheric  gas. 

The  bad  effects  caused  from  slow  cooling  are  eliminated  by 
quenching  the  deposit  at  the  proper  time  to  prevent  the  brittle 
structure  formation.  This  feature  is  greatly  facilitated  by  the 
use  of  the  arc  process  since  the  welding  can  be  interrupted  at  any 
time  and  the  deposit  quenched  without  greatly  interfering  with 
the  welding  progress. 

With  manganese  steel,  as  with  the  high  carbon  steel,  the  weld- 
ing is  facilitated  by  the  use  of  a  reverse  polarity;  i.  e.,  electrode 
positive. 

Non-Ferrous  Metals. — The  use  of  non-ferrous  electrode 
materials  has  been  rather  limited.  Bronze  low  in  zinc — not  over 
3  per  cent — and  pure  nickel,  and  nickel  alloy  materials  are  among 
those  which  have  been  used  commercially.  Generally  such  ma- 
terials are  used  with  a  reverse  polarity.  Few  or  no  data  have  been 
published  regarding  the  characteristics  when  used  for  welding. 

Fusion. — When  two  pieces  of  metal  are  melted  into  one 
mass  they  are  said  to  be  fused  together.  Welding,  therefore,  is 
one  continuous  operation  of  fusing  one  piece  of  metal  to  another. 
A  good  weld  is  one  where  this  fusion  is  complete.  If  the  metal 
being  added  or  the  surface  receiving  the  metal  is  not  thoroughly 
melted,  or  if  slag  or  gas  pockets  are  trapped,  the  fusion  will  be 
interrupted  and  the  weld  will  not  be  sound  because  of  the  lack  of 
thorough  fusion.  The  factors  which  determine  fusion  in  arc 
welding  are  arc  current  density,  arc  length,  and  arc  manipulation. 

The  arc  current  density  is  determined  by  the  thermal  capacity, 
composition  and  melting  point  of  the  work  piece  and  electrode.  If 
the  work  piece  is  massive  its  thermal  capacity  and  conductivity 
will  be  high  and  the  arc  current  density  required  will  be  more 
than  in  the  case  of  a  part  of  lesser  area  and  section.  A  short  arc 
must  be  maintained  to  secure  the  proper  current  density  at  the 
work  terminal  of  the  arc,  to  minimize  the  effects  of  oxygen  and 


TRAINING  OPERATORS  91 

nitrogen  of  the  air,  and  to  prevent  large  globular  formation ;  these 
are  almost  always  accompanied  by  gas  pockets  and  oxide  inclusion 
in  the  weld. 

The  fusion  is  effected  by  the  relative  melting  points  of  the  work 
piece  and  the  electrode.  For  the  present,  let  it  suffice  to  say  that 
for  a  bare  electrode  with  the  usual  polarity  used,  the  melting  point 
of  the  electrode  should  be  greater  than  that  of  the  part  to  be 
welded.  The  appearance  of  the  deposited  metal  will  be  indicative 
of  the  degree  of  correctness  of  the  factors  enumerated  above,  and 
adjustments  can  be  made  according  to  conditions.  The  depth  of 
the  arc  crater  will  indicate  the  extent  of  penetration  and  the  con- 
tour will  reveal  whether  or  not  the  added  metal  has  overrun  the 
fused  area  on  the  work  piece. 

By  the  proper  manipulation  of  the  arc,  the  oxides  unavoidably 
formed  can  be  floated  to  the  top  of  the  weld  in  the  form  of  scale, 
which  can  be  loosed  by  a  chisel  and  brushed  away  preparatory  to 
adding  another  layer  of  metal,  thus  preventing  the  unfused 
pockets  caused  by  slag  inclusions. 

Thermal  Disturbance. — Due  to  the  localized  heat  of  the  arc, 
the  difference  in  temperature  at  the  point  of  fusion  and  the  metal 
immediately  surrounding  it  is  very  great,  resulting  in  a  rapid  flow 
of  heat  from  the  weld  area.  This  in  turn  results  in  a  quenching 
action  on  the  hot  metal  adjacent  to  the  weld,  causing  the  forma- 
tion of  a  hard  and  brittle  zone.  The  larger  the  part  the  greater 
will  be  the  thermal  capacity  and  conductivity,  resulting  in  a 
greater  temperature  difference  within  narrow  limits  and  a  more 
pronounced  quenching  effect.  The  degree  of  hardness  of  the  zone 
subjected  to  the  rapid  cooling  will  be  governed  greatly  by  the 
carbon  content;  when  the  carbon  content  is  as  much  as  0.3  per 
cent.  If  the  part  is  to  be  machined  or  subjected  to  vibratory 
stresses,  it  should  be  annealed  after  welding.  High  carbon  steel 
should  be  allowed  to  cool  slowly  and  to  do  this  it  is  usually  neces- 
sary to  resort  to  pre-heating.  These  conditions  should  not  be  lost 
sight  of  if  disastrous  results  are  to  be  avoided. 

Low  carbon  steel  plates  and  shapes  of  at  least  y2  in.  thickness 
are  not  greatly  affected  by  the  localized  heat,  especially  if  the 
proper  electrode  current  density  and  welding  procedure,  as  pre- 
viously outlined,  are  employed,  because  here  the  section  is  heated 


92  ELECTRIC  ARC   WELDING 

through  and  the  heat  conductivity  is  not  sufficient  to  effect  a  rapid 
flow  of  heat  from  the  weld.  In  addition,  the  low  carbon  content 
of  the  usual  plate  material  is  favorable  in  this  respect. 

When  welding  light  plate  material  a  factor  which  must  receive 
consideration  is  the  effect  of  overheating  the  plate  during  welding. 
Overheating  causes  a  coarsening  of  the  grain  and  not  infrequently 
so  weakens  the  metal  as  to  cause  it  to  break  just  outside  the  weld, 
giving  rise  to  the  mistaken  idea  that  the  weld  is  better  than  the 
part  welded.  This  question  is  largely  up  to  the  operator  who  by 
regulating  the  different  factors  governing  the  heat  can  minimize 
the  effect  to  a  large  extent. 

Expansion  and  Contraction  of  Part  Welded. — Metals  ex- 
pand more  or  less  under  the  action  of  heat  with  a  consequent 
increase  in  volume.  On  cooling  they  return  to  their  original 
volume  and  dimensions.  If  the  entire  mass  of  a  body  is  uniformly 
heated  and  is  cooled  in  the  same  way  the  expansion  and  contrac- 
•  tion  have  no  bad  effects.  When,  however,  the  heat  is  applied  at 
one  point  the  metal  expands  at  this  particular  place  and  intro- 
duces internal  stresses,  often  of  great  magnitude. 

In  welding  the  expansion  and  contraction  effects  are  generally 
localized  in  the  vicinity  of  the  weld.  In  metallic  arc  welding 
difficulties  of  this  nature  are  less  than  with  other  welding  proc- 
esses, yet  the  question  must  be  given  consideration.  An  example 
of  such  a  case  is  that  of  a  crack  in  a  plate,  which  does  not  extend 
to  the  edge,  such  as  is  often  encountered  in  locomotive  fireboxes. 
If  there  is  no  free  space  when  the  edges  are  heated  they  will  ex- 
pand and  exert  a  force  at  the  ends  of  the  crack  which  will  usually 
further  extend  the  crack.  In  such  cases  in  beveling  the  edges  a 
free  space  or  opening  should  be  made  between  the  edges  to  allow 
room  for  the  expansion.  In  some  instances,  as  in  the  welding  of  a 
crack  in  cast  iron,  it  may  be  necessary  to  pre-heat  at  the  ends  of . 
the  crack. 

Contraction  of  Fused  Metal. — The  contraction  of  the  fused 
metal,  the  major  portion  of  which  is  the  added  metal,  constitutes 
the  greatest  difficulty.  Owing  to  the  sudden  uneven  cooling  of 
the  deposit,  stresses  are  trapped  in  the  weld.  These  "locked  in" 
stresses  are  governed  largely  by  the  welding  procedure  and  the 
composition  of  the  weld.  If  the  weld  is  thoroughly  annealed, 


TRAINING  OPERATORS 


93 


practically  all  of  the  stresses  will  be  relieved.  If  a  welding  pro- 
cedure is  adopted  to  prolong  the  cooling  and  if  the  metal  is  very 
ductile,  the  stresses  will  be  greatly  reduced. 

A  method  that  has  been  found  to  give  excellent  results,  and 
which  greatly  minimizes  the  distortion,  is  called  the  back-step 
method  (Fig.  44),  the  object  of  which  is  to  avoid  the  concentra- 
tion of  the  accumulated  stresses  which  are  set  up  by  compelling 


FIG.  44 — Work  Marked  off  in  Sections  Illustrates  the  Methods  of  Back 

Step  Welding 

a  slight  giving  of  the  weld.  This  method  of  welding  is  performed 
as  follows : 

If  the  opening  is  slightly  greater  at  X  than  at  Y ,  the  welding 
should  progress  from  Y  to  X  and  each  section  should  be  welded 
in  numerical  order  and  in  the  direction  as  shown  by  arrows ;  i.  e., 
the  sections  from  1  to  7,  inclusive,  be  welded  by  starting  at  B, 
section  1,  filling  in  to  point  A;  returning  to  point  C,  section  2, 
filling  in  to  point  B,  section  1 ;  starting  at  point  D,  filling  in  to 
point  C ';  and  so  on  in  this  manner  until  all  the  sections  are  com- 
pleted. Each  section  should  be  practically  finished  before  starting 
the  next.  The  length  of  each  section  on  any  seam  should  not 
exceed  approximately  15  in.  and  for  short  seams  should  be  rela- 
tively shorter.  The  work  may  be  stopped  at  any  time  without 
fear  of  cracking,  provided  that  the  portion  of  the  seam  gone  over 
is  finished  flush. 

Methods  to  Overcome  Bad  Effects  of  Contraction  Stresses. 


94 


ELECTRIC  ARC   WELDING 


—If  two  pieces  of  metal  are  allowed  to  lie  loosely,  free  to  move, 
they  will  warp  and  distort  in  their  relative  positions  during  the 
process  of  welding  unless  the  proper  procedure  is  followed.  If 
they  are  rigid  the  stresses  which  are  set  up  will  be  taken  up  almost 
entirely  by  a  slight  giving-in  of  the  weld,  providing  the  weld  is 
ductile,  so  that  when  the  parts  are  released  there  is  no  tendency 
for  them  to  spring  out  of  shape,  nor  is  there  any  apparent  lack 
of  strength  which  can  be  regained  by  supposedly  releasing  the 
stresses  with  annealing.  This  point  is  reassuring  in  that  it  indi- 
cates that  rigid  parts  may  be  safely  welded  and  no  serious  stresses 


FIG.  45 — Arrows  Indicate  Strains  Produced  by  Cooling  of  the  Metal  in 

the  Weld 

left  in  the  weld,  provided  the  welding  is  done  properly ;  i.  e.,  if  the 
weld  is  not  brittle  and  a  method  is  employed  to  prevent  the  con- 
traction strains  from  accumulating  and  concentrating  at  any  one 
point,  the  total  of  which  may  in  some  cases  be  sufficient  to  cause 
a  fracture. 

For  example,  if  the  edges  of  two  ^  in.  plates  are  beveled  and 
aligned  for  welding,  as  shown  by  Fig.  45,  and  the  welding  is 
started  at  A  and  continued  in  the  direction  of  C,  as  the  hot  ex- 
panded metal  is  added  between  the  beveled  edges  it  will  on  cooling 
contract  and  draw  the  edges  closer  together  at  the  point  C.  This 
would  continue  as  the  welding  progressed  in  the  same  direction, 
at  least  until  the  weld  became  cool  at  the  point  where  the  welding 
was  started.  If  now  the  welding  be  continued  from  B  to  C}  as  the 
hot  metal  placed  in  the  V  contracts  it  will  tend  to  further  draw 


TRAINING  OPERATORS  95 

the  edges  together  at  C,  which  will  place  a  strain  at  A,  as  indi- 
cated by  the  arrows. 

Inspection  and  Examination  of  Welds. — A  visual  examina- 
tion of  welds  will  reveal  more  than  is  commonly  admitted.  The 
workmanship  will  be  indicated  by  the  uniformity  of  the  deposit 
surface,  showing  ability  to  maintain  a  uniform  arc;  the  deposit 
contour  will  indicate  the  extent  of  the  overlap,  if  any.  The  ap- 
pearance of  the  under  side  of  the  joint  will  show  the  extent  of  the 
fusion  at  the  bottom  of  the  scarf.  The  extent  of  the  porosity  and 
slag  is  as  an  index  to  the  correctness  of  arc  current,  arc  length, 
and  the  state  of  cleanliness  in  which  the  work  is'  done,  etc. 

Examination  of  sample  welds  by  the  operators  is  advisable  in 
order  that  they  may  know  their  aptitude  and  their  shortcomings. 
A  great  deal  can  be  done  even  without  the  use  of  special  apparatus 
by  the  simple  bending  to  the  breaking  point  and  by  the  corrosion 
test. 

The  bending  test  is  made  by  welding  together  two  pieces  ap- 
proximately 3  in.  wide  x  4  in.  long  to  form  a  sufficient  total  length 
to  facilitate  bending.  One  end  is  then  placed  in  a  vise  or  some 
other  form  of  clamp  so  that  the  line  of  welding  is  just  above  the 
edge  of  the  vise.  The  piece  is  then  bent  by  striking  with  a  ham- 
mer. If  the  plate  is  welded  from  one  side  it  should  be  bent  so 
that  the  top  or  welt  of  the  weld  will  be  in  the  folds  of  the  bend. 
When  a  satisfactory  angle  is  reached  the  bending  may  be  com- 
pleted in  a  press  or  by  other  means.  The  angle  should  be  observed 
when  the  weld  begins  to  crack.  Bending  should  then  be  con- 
tinued until  the  piece  breaks.  This  test  will  not  only  show  the 
ductility  by  the  angle  of  the  bend  before  cracking,  but  the  ap- 
pearance of  the  fracture  will  reveal  the  thoroughness  of  fusion, 
extent  of  slag  inclusions,  air  pockets,  etc. 

Another  test  which  may  be  made  in  the  shop  is  that  of  chipping 
and  calking  with  a  chisel  to  ascertain  the  fusion  between  added 
and  parent  metal,  and  to  determine  roughly  the  ductility,  hardness 
and  toughness  of  the  deposit. 

The  soundness  of  a  weld— i.  e.,  whether  or  not  the  joint  is 
steam,  gas  or  liquid  tight— may  be  determined  by  the  penetration 
test.  While  there  are  a  number  of  methods  to  determine  this,  the 
most  convenient  one  at  the  present  time  is  by  the  use  of  kerosene. 


96  ELECTRIC  ARC   WELDING 

By  wetting  the  surface  of  a  weld  on  one  side  with  kerosene  any 
unsoundness,  due  to  a  chain  of  slag  inclusions,  air  pockets,  in- 
complete fusion  or  porosity,  that  extends  completely  through  the 
section,  will  be  detected  by  the  penetration  of  the  kerosene 
through  to  the  opposite  side. 

The  corrosion  test  is  made  by  welding  together  the  edges  of 
two  y%  in.  or  y2  in  plates  and  cutting  the  plate  perpendicular  to 
the  line  of  weld.  The  welded  section  is  then  polished,  by  filing 
first  with  a  rough  file,  then  with  a  smooth  one.  The  filing  is 
followed  by  a  series  of  polishings  with  emery  papers  of  increasing 
fineness  until  a  distinct  polish  is  obtained.  Avoid  touching  the 
surface  with  the  fingers  so  that  it  will  not  become  greasy.  At  this 
stage  of  the  corrosion  test  one  always  has  the  impression  that  the 
weld  is  perfect.  The  defects,  however,  will  not  be  revealed  until 
the  etching  liquid  is  applied.  For  this  purpose  a  solution  of  one 
part  concentrated  nitric  acid  in  ten  parts  water  may  be  used.  If 
inspectors  or  welders  apply  this  test  occasionally,  much  time  will 
be  saved  in  perfecting  the  proper  methods  for  different  metals  to 
secure  the  best  results. 

From  the  foregoing,  it  is  evident  that  if  full  advantage  is  taken 
of  the  many  resources  at  the  disposal  of  those  associated  with 
welding,  the  uncertainties  of  the  process  will  be  reduced  to  a 
point  to  where  the  art  will  attain  recognition  as  a  means  of  effi- 
cient production. 


VI 


CARBON  ARC  WELDING  AND  CUTTING 

In  general,  carbon  arc  welding  is  performed  in  a  manner  similar 
to  that  of  the  oxy-acetylene  welding  process.  Here,  as  in  the  case 
of  the  metallic  arc,  the  arc  serves  to  transform  electrical  energy 
into  thermal  energy.  The  heat  liberated  at  the  positive  terminal, 
or  work  side  of  the  arc,  serves  to  melt  the  parent  metal,  while  the 
heat  of  the  arc  stream  is  utilized  to  melt  the  filler  rod.  The  ques- 


-  '(6  Brass  Screw  wHh  'g  Hole 
in  Head  for  Inserting 
Wire  for  Turn  Screw 


FIG.  46 — Adapter  Used  for  Low  Current  Values  and  Intermittent  Welding 

tion  of  proper  arc  current,  arc  length,  electrode  diameter  and 
filler  material,  has  previously  been  discussed  and  needs  no  further 
comment. 

Equipment. — The  equipment  required  will  vary  depending 

97 


98  ELECTRIC  ARC   WELDING 

upon  the  nature  of  the  work.  The  same  characteristics  of  the 
welding  circuit  are  required  for  the  carbon  arc  as  for  the  metallic 
arc. 

For  thin  work  the  same  equipment  as  used  for  metallic  arc 
welding  may  be  used  for  the  carbon  arc,  providing  the  power 
required  does  not  exceed  the  kilowatt  rating  of  the  machine.  For 
low  current  values  and  intermittent  welding  an  adapter,  as  shown 
by  Fig.  46,  may  be  used  with  the  metallic  electrode  holder. 

Where  the  carbon  arc  is  used  it  is  obviously  necessary  to  use  a 
helmet  type  of  face  shield  and  for  currents  greater  than  200  am- 
peres a  special  holder,  as  shown  elsewhere  in  this  book,  is  required 
to  protect  the  operator  from  the  intense  heat  of  the  arc  and  to  pro- 
vide ample  carrying  capacity  for  the  current. 

Movement  and  Position  of  Carbon  with  Relation  to  Work. — 
Experience  has  shown  that  the  arc  stream  can  be  controlled  more 
easily  if  the  carbon  is  inclined  slightly  from  a  vertical  position. 
The  direction  of  travel  and  the  melting  of  the  filler  rod  is  also 


FIG.  47 — Correct    Position    of    Graphite    Electrode   and   Filler   Rod    with 
Relation  to  Work 

facilitated  when  the  electrode  is  inclined  as  shown  by  Fig.  47. 

The  manipulation  of  the  arc  will  vary  with  the  nature  of  the 
work  and  the  different  operators.  The  function  of  the  manipula- 
tion is  to  heat  the  parent  metal  to  the  proper  state  of  fusion  so 
that  when  the  filler  metal  is  melted  into  the  weld  the  two  will 
alloy  immediately  with  each  other.  If  the  filler  rod  is  melted 
before  the  parent  metal  is  at  the  proper  state  of  fusion  the  result 
will  be  adhesion  and  not  a  weld.  It  is  a  question  then  of  relying 


CARBON  ARC  WELDING  AND  CUTTING  99 

upon  the  operator  to  so  conduct  the  work  as  to  obtain  thorough 
fusion  between  the  parent  and  the  added  metal. 

Welding  by  the  metallic  or  carbon  arc  is  but  a  regular  succes- 
sion of  "molten  baths"  joined  one  to  the  other  so  as  to  form  a 
homogeneous  line.  There  are  certainly  methods  which  must  be 
learned,  but  these  are  relatively  easy  to  acquire  and  are  better 
obtained  by  practice  than  by  reading.  The  most  important  advice 
which  must  be  given  to  the  welder  concerns  the  simultaneous  and 
uniform  melting  of  the  surface  to  which  metal  is  to  be  added  and 
of  the  filler  rod. 

The  most  common  practice  where  the  addition  of  metal  is 
necessary  is  to  play  the  arc  on  the  part  to  be  welded  until  a  small 
spot  is  heated  to  a  molten  state.  At  this  moment  the  filler  rod  is 
intermittently  interposed  into  the  arc  stream,  care  being  taken  to 
melt  the  rod  in  comparatively  fine  drops  so  that  the  added  metal 
will  not  overrun  the  fused  spot.  This  operation  is  progressively 
repeated  until  the  weld  is  completed. 


FIG.  48 

By  regulating  the  addition  of  metal  so  as  to  maintain  the  fused 
spot  on  the  parent  metal  the  chances  for  unfused  sections  will  be 
greatly  reduced.  It  is  desired  here  to  recall  that  all  the  precau- 
tions given  elsewhere  for  the  regulation  of  the  arc  lengths  and 
current  should  be  carefully  observed. 

To  facilitate  the  building  up  of  flat  surfaces  carbon  blocks  or 
paste,  and  in  some  cases  metal  rods,  are  used  for  making  forms 
to  confine  the  metal  within  certain  limits. 

An  application  to  which  the  carbon  arc  is  particularly  adapted, 
where  strength  is  not  important,  is  in  the  joining  of  edges  simply 
by  melting  them  together  without  the  use  of  a  filler  rod.  Usually 
when  this  is  done  the  edges  are  upturned  and  welded  as  shown 
by  Fig.  48. 

The  quality  of  carbon  arc  welds,  as  commercially  obtained,  is 
as  yet  a  question.  It  is  an  admitted  fact  that  the  difficulty  in 
manipulating  a  carbon  arc  is  somewhat  greater  than  the  difficulty 
of  manipulating  an  oxy-acetylene  flame.  The  reason  that  the  arc 


100  ELECTRIC  ARC   WELDING 

is  more  difficult  to  manipulate  is  that  the  operator  must  use  the 
full  temperature  of  the  arc  or  break  it  entirely — there  is  no  inter- 
mediate point.  With  oxy-acetylene  if  the  operator  believes  he  is 
getting  the  metal  too  hot  he  can  merely  withdraw  the  flame  from 
the  weld,  and  thus  reduce  the  temperature,  but  without  breaking 
the  continuity  of  heat.  The  particular  difficulty  encountered  in 
carbon  arc  welding,  owing  to  this  fact,  arises  in  the  case  of  thin 
sections  where  the  tendency  is  for  the  arc  to  burn  through,  or 
when  welding  on  a  vertical  surface.  The  temperature  of  the  arc 
is  so  high  that  the  metal  runs  rapidly  making  it  extremely  difficult 
to  weld  in  positions  other  than  flat.  With  the  oxy-acetylene  flame 
the  heat  may  be  reduced  by  varying  the  distance  of  the  flame  from 
the  work ;  the  metal  can  thus  be  maintained  in  such  a  plastic  state 
that  a  weld  can  be  accomplished. 

While  these  difficulties  tend  to  impair  the  usefulness  of  the 
process  they  do  not  by  any  means  condemn  it.  In  most  cases  a 
method  of  welding  can  be  adopted  such  that  these  difficulties  may 
be  made  almost  negligible.  At  the  present  time  a  considerable 
amount  of  thin  sheet  work,  such  as  steel  barrels,  transformer 
cases,  etc.,  are  welded  by  the  carbon  arc  process  by  both  auto- 
matic and  hand  welding.  Some  carbon  arc  welding  has  been 
done  by  distributing  short  pieces  of  wire  along  the  seam  formed 
by  abutting  plate  edges  and  playing  the  arc  over  the  seam  until 
the  wire  pieces  and  edges  are  melted  into  one  mass.  The  object 
of  this  method  is  to  increase  the  area  of  the  weld  over  that 
obtained  where  the  edges  are  simply  melted  together  without  any 
metal  being  added. 

A  recent  development  in  carbon  arc  welding  for  light  work  is 
the  use  of  a  comparatively  high  arc  potential — about  75  volts  with 
a  relatively  low  arc  current.  Working  data  have  not  as  yet  been 
published  for  welding  of  this  nature.  The  results  obtained  by 
experiments  in  this  direction,  however,  warrant  further  research 
along  this  line. 

There  are  a  number  of  chances  for  defects  when  welding  heavy 
sections  by  the  carbon  arc.  The  first  is  lack  of  penetration,  or  as 
sometimes  expressed,  "not  welded  through."  This  takes  place 
when  the  edges  are  not  beveled,  and  because  of  lack  of  sufficient 
heat  and  manipulation  to  permit  the  entire  scarf  to  become  thor- 


CARBON  ARC  WELDING  Atfb'  CUTTING  J        ^1 


oughly  fused.  Poor  fusion  is  sometimes  caused  by  the  melting 
down  of  the  edges  before  the  bottom  of  the  "V"  is  melted,  or  by 
the  interposition  of  slag  layers.  This  is  generally  caused  by  a 
supply  of  molten  metal  on  metal  already  solidified,  or  to  a  lack  of 
liquefaction  of  the  part  constituting  the  weld.  Blowholes  are  a 
common  source  of  weakness  in  welds  and  are  thought  to  be  due 
principally  to  the  carbon  monoxide  gas  formed  from  the  carbon 
in  the  arc  terminals  and  filler  rod,  the  gas  being  trapped  by  the 
rapid  solidification  of  the  metal. 

Effects  of  Heat  on  Neighboring  Metal.  —  The  heat  absorbed 
by  the  welded  part  produces  internal  stresses  due  to  expansion 
and  contraction.  If  the  mass  of  the  part  welded  is  sufficient  to 
cause  rapid  cooling,  especially  when  the  carbon  content  is  in 
excess  of  0.3  per  cent,  a  hard  brittle  line  will  be  formed  adjacent 
to  the  melted  metal.  This  can  be  removed  by  annealing  after 
welding.  This  will  not  be  necessary  in  most  cases,  however,  as 
the  area  heated  usually  forms  a  large  proportion  of  the  part 
welded  and  there  will  not  be  a  great  difference  in  temperature 
within  narrow  limits. 

Parts  ordinarily  difficult  to  weld  with  the  metallic  arc,  such  as 
cast  iron  and  non-ferrous  metals,  can  as  a  rule  be  welded  by  the 
carbon  arc.  Copper  and  bronzes,  low  in  zinc  and  tin,  can  be 
welded.  By  the  use  of  fluxes  many  other  alloys  of  both  ferrous 
and  non-ferrous  metals  may  be  welded.  Lead  or  other  low  melt- 
ing point  metals  may  be  welded  by  holding  the  carbon  or  graphite 
electrode  in  contact  with  the  surface  to  be  melted,  allowing  the 
carbon  to  become  heated  to  an  incandescence  without  drawing  an 
arc  ;  the  incandescent  electrode  end  serves  to  melt  the  surface  and 
metal  to  be  added.  The  process  is  used  extensively  in  lead  storage 
battery  work. 

Cutting  or  Melting.  —  The  heat  of  the  carbon  arc  can  be  used 
to  cut  metals  ;  the  heat  of  the  arc  simply  serves  to  melt  the  metal 
and  is  unlike  those  processes  where  oxygen  is  utilized  to  effect  the 
cutting  by  rapid  oxidation.  The  cutting  is  accomplished  by  main- 
taining the  arc  at  one  location,  as  for  example  at  the  edge  of  a 
plate,  until  the  heat  is  sufficient  to  cause  the  metal  to  melt  and  run; 
the  arc  is  then  advanced  at  the  same  rate  as  the  section  is  melted. 
On  heavy  sections  the  cutting  is  started  at  the  bottom  edge  tQ 


102  *  ELECTRIC  ARC   WELDING 

facilitate  the  escape  of  the  metal;  the  inability  conveniently  to  dis- 
pose of  the  molten  metal  constitutes  one  of  the  objections  to 
carbon  arc  cutting1.  The  excessive  amount  of  metal  removed — 
i.  e.,  the  width  of  the  cut — together  with  the  seemingly  unavoid- 
able ragged  edges  prevent  the  process  from  competing  with  the 
oxidizing  processes  for  most  purposes.  Fig.  49  gives  some  con- 
ception of  the  appearance  of  a  cut  made  with  a  graphite  electrode. 


JL_. 


FIG.  49— Illustration  of  Ragged  Edges  Produced  on  Plate  Material  when 
Cut  by  the  Carbon  Arc    • 

The  width  of  a  cut  with  a  300-ampere  arc  on  y2  in.  plate  will 
be  about  ^  in.  and  the  rate  of  cutting  will  be  approximately  3.5 
in.  per  minute ;  while  with  a  500-amp.  arc  the  width  of  the  cut  will 
be  about  %  in-  and  the  rate  approximately  6  in.  per  minute.  The 
arc  diameter  increases  as  the  square  root  of  the  current,  so  that 
the  width  of  the  cut  will  always  increase  with  an  increase  in  the 
arc  current.  In  spite  of  these  unfavorable  conditions  the  carbon 
arc  is  used  extensively  for  cutting  up  scrap  metal;  cutting  off 
risers  and  fins  from  cast  iron,  cast  steel,  and  non-ferrous  metals ; 
melting  of  surfaces  to  improve  the  appearance,  etc.  Where  a 
great  deal  of  work  of  this  kind  is  to  be  done  the  process  will  no 
doubt  effect  economy  over  the  oxy-acetylene  process. 

Where  only  occasional  cutting  is  done  on  a  considerable  variety 
of  work  and  when  neat,  accurate  work  is  required,  the  oxy-acety- 
lene process  is  generally  used.  Due  to  the  low  initial  cost  of  the 
equipment,  as  compared  to  the  electric  arc  process,  and  its  inher- 
ent adaptability  to  the  cutting  of  iron  and  steel,  the  process  has 


CARBON  ARC  WELDING  AND  CUTTING  103 

become  an  adjunct  to  most  all  industries  using  iron  and  steel. 
The  fact  that  the  process  is  used  extensively  for  preparing  work 
to  be  arc  welded,  especially  with  the  metallic  arc,  and  since  the 
arc  welding  operator  is  often  required  to  prepare  his  own  work  by 
the  use  of  the  oxy-acetylene  flame,  a  brief  description  of  the 
process  is  furnished  with  the  hope  that  it  will  assist  the  student 
welder  in  forming  a  basic  idea  of  the  principle  of  cutting  by 
oxidation. 

Cutting  or  Burning  of  Iron  and  Steel  by  Oxidation. — In 
general,  the  cutting  or  burning  of  wrought  or  ingot  iron  and  steel 
amounts  to  the  utilization  of  oxygen  to  support  combustion  of  the 
metal,  resulting  in  oxidation  and  reduction.  Ignoring  processes 
of  oxidation  or  reduction  simply  brought  about  by  heat  or  some 
other  form  of  energy,  in  the  actual  process  the  oxidizing  agent 
suffers  reduction  and  the  reducing  agent  oxidation. 

Most  metals  oxidize  under  the  action  of  the  oxygen  of  the  air. 
This  slow  combustion  continues  until  the  layer  of  oxide  is  dense 
enough  to  protect  the  rest  of  the  metal  from  the  action  of  the  air, 
as  in  the  case  of  iron  for  example.  This  action  of  the  oxygen  of 
the  air  is  greatly  intensified  as  the  temperature  of  the  metal  is 
raised,  and  a  very  rapid  action  is  secured  where  practically  pure 
ogygen  is  concentrated  at  a  point  on  a  piece  of  iron  which  has 
been  heated  to  a  red  heat.  For  example,  if  a  thin  piece  of  iron 
or  steel  in  a  spiral  form  is  suspended  inside  a  jar  of  oxygen  after 
first  raising  the  lower  end  to  a  red  heat,  the  iron  burns  rapidly  in 
contact  with  the  gas.  The  oxide  of  iron  which  is  formed  is  de- 
tached from  the  metal  and  is  projected  on  all  sides  in  a  molten 
state. 

The  oxidation  commences  at  a  point  which  has  previously  been 
heated  to  redness,  because  at  this  temperature  the  reaction  takes 
place  readily.  The  combustion  of  this  portion  of  iron  produces 
heat,  a  portion  of  which  is  absorbed  by  the  neighboring  part. 
This  is  sufficient  to  raise  it  to  red  heat  so  that  it  in  turn  burns, 
and  this  reaction  is  progressively  propagated  throughout  the 
metal.  The  oxide  formed  has  a  lower  melting  point  than  that  of 
the  metal,  and  is  detached,  leaving  the  iron  continually  clean. 

Iron  and  steel  are  alone  amongst  the  ordinary  metals  which  can 
be  burnt  in  a  continuous  manner  by  contact  with  oxygen,  because 


104  ELECTRIC  ARC   WELDING 

the  oxide  of  iron  produced  by  the  combustion  is  eliminated,  in 
proportion  as  it  is  formed,  in  the  molten  state.  It  is  almost  use- 
less to  attempt  to  apply  the  process  to  other  metals  or  alloys 
which  in  contact  with  oxygen  have  a  slower  rate  of  oxidation, 
and  whose  oxide  has  a  melting  point  equal  to  or  higher  than  that 
of  the  metal,-  which  would  prevent  it  from  being  detached.  Cop- 
per, brass  and  aluminum  are  examples  of  metals  of  this  character. 

High  carbon  steels,  the  melting  point  of  which  is  lower  than 
that  of  pure  iron  and  near  the  melting  point  of  the  oxide,  do  not 
lend  themselves  well  to  cutting;  there  is  also  the  difficulty  of 
eliminating  the  oxides  from  the  molten  metal. 

The  question  of  oxidation  has  been  gone  into  briefly  in  order  to 
distinguish  between  the  cutting  or  burning  process  where  the. oxy- 
gen is  used  mainly  to  support  combustion  of  the  iron  or  steel,  and 
the  welding  process  where  the  oxygen  is  used  entirely  to  support 
combustion  of  the  acetylene  gas  whose  heat  is  utilized  to  melt  the 
metal  which  is  to  be  welded. 

In  the  practical  application  of  the  principle  of  oxidation  to  the 
cutting  of  wrought  or  ingot  iron  and  steel,  the  heat  of  the  reaction 
is  not  sufficient  to  maintain  the  temperature  necessary  for  the 
oxidation  of  the  adjoining  portion,  as  was  the  case  in  the  example 
of  the  thin  strip  plunged  into  a  jar  of  oxygen.  The  conductivity 
of  the  metal  to  be  cut  is  so  great  and  so  much  of  the  heat  is 
absorbed  that  the  temperature  necessary  for  the  oxidation  cannot 
be  maintained  without  the  addition  of  sufficient  heat  to  replace 
the  losses  by  conduction  and  radiation,  thus  maintaining  the 
metal  at  a  red  heat. 

Cutting  Blow-Pipes.— The  cutting  blow-pipe  consists  of  an 
arrangement  giving  a  small  pre-heating  flame,  which  is  usually 
oxy-acetylene  since  the  welding  as  well  as  the  cutting  can  be  done 
with  these  gases ;  as  a  matter  of  fact  oxy-hydrogen,  oxy-gas,  oxy- 
benzole  flames,  or  any  good  hydro-carbon  gas  can  be  used  with 
success  for  the  pre-heating  flame  for  cutting;  here  it  is  simply  a 
case  of  heating  the  metal  and  not  melting  it,  so  that  they  do  not 
have  the  same  disadvantages  as  in  the  case  of  autogenous  welding. 

The  oxy-hydrogen  flame  is  long,  whereas  the  oxy-acetylene 
flame  is  short,  so  that  on  heavy  parts  the  pre-heating  extends 
deeper;  because  of  this,  hydrogen  is  claimed  by  some  to  be 


CARBON  ARC  WELDING  AND  CUTTING  105 

superior  to  acetylene  for  cutting.  Independent,  but  in  the  same 
blow  pipe,  is  an  arrangement  for  bringing  to  the  tip  the  cutting 
oxygen,  regulating  it,  and  projecting  it  on  the  metal. 

In  the  earlier  days  the  blowpipes  were  arranged  with  a  heating 
jet  preceding  the  oxygen  jet,  which  necessitated  the  moving  of 
the  torch  in  one  direction.  Later  torches,  however,  are  arranged 
so  that  the  blowpipe  can  be  moved  in  any  direction ;  this  is  accom- 
plished by  surrounding  the  oxygen  orifice  with  a  number  of 
small  pre-heating  jets.  The  construction  of  the  cutting  blow-pipe 
has  an  importance  which  the  user  should  recognize  to  the  extent 
of  analyzing  the  safety  and  economical  features  sufficiently  to 
be  able  to  choose  a  commercially  good  cutting  blow-pipe.  Atten- 
tion has  been  drawn  to  certain  research  which  may  be  taken  to 
indicate  that  improvements  in  the  efficiency  of  cutting  by  oxida- 
tion can  be  looked  forward  to  in  the  not  far  distant  future — one 
possibility  which  has  been  suggested  is  that  of  pre-heating  the 
oxygen. 

It  is  not  believed  to  be  important  to  describe  in  detail  here  the 
construction,  or  to  attempt  to  give  instructions  as  to  its  operation, 
since  this  information  is  always  supplied  by  each  manufacturer 
for  his  particular  design  of  blowpipe  as  v/ell  as  for  the  acces- 
sories, such  as  the  regulators,  fittings,  etc. 

The  purity  of  the  oxygen  is  an  important  factor  in  the  work 
of  cutting,  especially  for  the  fixing  of  the  cost. 

Methods  of  Obtaining  Oxygen. — The  two  processes  of  ob- 
taining oxygen  in  general  use  are  the  electrolytic,  and  liquid  air. 
The  oxygen  made  by  the  electrolytic  process  is  usually  very  pure. 
Gas  98  per  cent  pure  should  be  obtained  direct  from  the  cells  and 
when  purified  it  will  exceed  99  per  cent  purity.  In  the  electrolytic 
process  two  cubic  feet  of  hydrogen  gas  are  generated  for  each 
cubic  foot  of  oxygen.  It  is  of  extreme  importance  that  these 
gases  do  not  become  mixed  as  a  mixture  even  so  low  in  hydrogen 
as  5  per  cent  hydrogen  and  95  per  cent  oxygen  will  explode. 

There  is  little  or  no  danger,  however,  with  oxygen  furnished 
from  reputable  concerns,  some  of  whom  guarantee  freedom  from 
danger  of  this  character. 

The  liquid  air  process  of  obtaining  oxygen  is  a  refrigeration 
process.  The  air  is  liquefied  by  expansion  after  having  been 


106  ELECTRIC  ARC   WELDIXG 

compressed.  The  nitrogen  is  then  allowed  to  evaporate,  leaving 
liquid  oxygen.  The  liquid  oxygen  is  then  allowed  to  come  to  a 
gaseous  state,  when  it  is  placed  in  holders,  from  which  it  is  com- 
pressed into  steel  drums,  usually  of  200  cu.  ft.  capacity  com- 
pressed to  about  1800  Ib.  pressure  per  square  inch.  This  process 
is  widely  known  as  the  Linde  air  oxygen,  Linde  being  the  name  of 
one  of  the  inventors  of  the  process.  After  one  or  more  processes 
of  purification  this  oxygen  is  from  97  per  cent  to  99  per  cent  pure. 
The  efficiency  of  oxygen  is  greatly  decreased  by  impurities.  This 
is  more  noticeable  in  cutting  than  in  welding.  One  per  cent  im- 
purity is  apparent  in  cutting,  not  only  in  the  efficiency  of  the 
oxygen  but  in  the  appearance  of  the  cut. 

Oxygen  is  a  colorless,  tasteless  gas.  It  is  the  most  abundant 
and  most  widely  distributed  of  all  the  elements,  constituting  by 
weight  more  than  one-fifth  of  the  air  and  eight-ninths  of  the 
water.  It  is  slightly  heavier  than  air,  weighing  1.105  times  more 
than  air.  One  cubic  foot  of  oxygen  weighs  .08921  Ib. 

Oxygen  expands  with  an  increase  in  temperature,  so  that  an 
arbitrary  figure  has  been  chosen  as  a  standard  from  which  to 
measure  it ;  this  figure  is  68  deg.  F.  to  70  deg.  F.,  depending  upon 
the  company  furnishing  the  oxygen.  For  each  one  degree  change 
in  temperature  Fahrenheit  there  is  a  corresponding  change  in 
pressure  of  approximately  3.42  Ib.  It  is  thus  evident  that  oxygen 
tanks  should  not  be  subjected  to  high  temperatures  \vhich  may 
raise  the  pressure  to  a  value  which  would  jeopardize  the  safety  of 
the  gages,  hose,  etc. 


VII 

ELECTRODE  MATERIALS  FOR  METALLIC 
ARC  WELDING 

Electrodes  for  arc  welding  generally  consist  of  either  carbon, 
graphite  or  metallic  rods.  In  either  case  the  electrode  is  the  part 
manipulated  by  the  operator  and  is  one  of  the  two  parts  between 
which  the  arc  is  formed. 

Bare  Metallic  Electrodes — Sizes,  and  Chemical  Composi- 
tion.— The  metal  electrode  most  commonly  used  at  the  present 
time  consists  of  bare  mild  steel  or  ingot  iron  wire  especially  drawn 
and  alloyed  for  welding  purposes.  The  prime  requisite  for  an 
electrode  is  that  it  should  possess  the  necessary  qualities  which 
will  make  it  possible  to  produce  a  sound  homogeneous  weld.  To 
secure  this  result,  the  metal  in  passing  from  the  electrode  into  the 
weld  must  be  liquid  in  a  uniform,  finely  divided  state,  thus  per- 
mitting a  close  concentrated  arc,  which  insures  the  proper  state 
of  fusion  at  the  point  on  the  work  opposite  the  end  of  the  elec- 
trode, so  that  when  the  liquid  particles  strike  this  fused  spot  they 
will  unite  and  solidify  with  it. 

If  the  metal  is  transferred  in  large  globules  the  arc  will  not 
concentrate  the  heat  sufficiently  on  the  work  to  insure  the  proper 
state  of  fusion,  in  which  case,  when  the  globules  strike  the  work 
they  will  adhere  without  fusion,  thus  causing  a  bad  weld.  It  will 
also  be  found  difficult  to  direct  the  metal  where  it  is  desired,  and 
the  deposited  metal  in  the  weld  will  be  found  more  brittle,  due  to 
the  increased  oxidation,  as  a  result  of  the  long  arc  necessitated  by 
the  large  globular  formation  and  the  lateral  spreading  of  the  arc. 
Any  physical  or  chemical  variation  in  electrode  material  must 
therefore  be  accomplished  without  detrimental  effect  upon  the 
weldability  requirements  mentioned. 

Electrode  sizes. — The  sizes  most  commonly  used  for  electrodes 

are  as  follows : 

107 


108  .       ELECTRIC  ARC   WELDING 

Fractions  of  an  Inch  Decimals  of  an  Inch 

A  0.0625 

3%  0.0938 

%  0.1250 

&  0.1563 

&  0.1875 

%  0.2500 

The  use  of  wire  or  sheet  metal  gages,  as  expressed  in  terms  of 
B.  &  S.,  A.  W.  G.,  etc.,  to  designate  electrode  diameters  is  con- 
fusing and  therefore  is  not  recommended.  Electrode  diameters 
should  be  expressed  in  mils  (thousandths  of  an  inch).  The 
allowable  tolerance  plus  or  minus  should  not  be  greater  than  six 
mils.  The  importance  of  this  will  be  appreciated  by  simply  calling 
attention  to  the  close  relation  of  the  current  density  to  the  elec- 
trode diameter,  which,  however,  is  not  directly  proportional  to 
the  diameter.  Expressed  in  mils,  the  sizes  most  commonly  used 
are  156  mils,  125  mils  and  188  mils.  The  nature  of  the  industry, 
of  course,  will  determine  the  quantity  of  the  different  sizes  to  be 
used.  On  railroads  and  in  shipyards  the  demand  for  the  dif- 
ferent sizes  is  in  the  same  order  as  the  sizes  given  above. 

The  length  of  the  electrode  commonly  used  is  14  in.  In  some 
cases  the  material  is  purchased  in  coils  and  is  then  cut  into  con- 
venient lengths.  This  is  not  considered  the  best  practice,  how- 
ever, as  the  small  additional  ,cost  of  the  straight  cut  material  will 
be  more  than  offset  by  the  cost  of  the  time  saved  in  handling  by 
the  operator. 

The  elements  usually  present  in  mild  steel  electrodes,  upon 
which  limitations  are  generally  placed,  are  carbon,  manganese, 
copper,  silicon,  phosphorus  and  sulphur.  Little  or  no  attention 
has  been  given  to  the  gas  content  present  in  solution  since  the 
total  does  not  usually  exceed  0.1  per  cent. 

Carbon. — The  maximum  carbon  content  in  the  usual  mild 
steel  electrode  material  does  not  exceed  0.18  per  cent.  Some 
welding  engineers  contend  that  the  carbon  present  in  the  usual 
soft1  steel — 0.08  to  0.15  per  cent — is  desirable  as  it  improves  the 
welding  characteristics  by  forming  carbon  monoxide  gas,  which 
on  expanding  assists  in  the  transfer  of  the  liquid  metal  from  elec- 
trode to  plate.  The  theory  has  also  been  advanced  that  the  gas 


ELECTRODE  MATERIALS  109 

formed  from  the  carbon  envelops  the  arc  stream  and  offers  a 
degree  of  protection  to  the  metal  from  the  atmosphere. 

Ori  the  other  hand,  there  are  some  who  favor  the  ingot  iron  ma- 
terial, which  is  practically  free  from  carbon  or  manganese.  This 
material  is  sometimes  called  American,  Norway  or  Swedish  iron, 
and  is  extensively  used  in  oxy-acetylene  welding.  The  ingot  iron 
electrode  material  when  properly  made  is  known  to  possess  good 
welding  characteristics;  this  fact  tends  to  minimize  the  impor- 
tance of  the  expansion  of  carbon  monoxide  gas  as  a  factor  in  the 
transfer  of  the  liquid  metal  from  the  electrode  to  plate  material, 
and  tends  to  support  the  theory  that  the  metal  transfer  is  due 
principally  to  the  forces  of  molecular  attraction,  gravity,  surface 
tension,  adhesion  and  cohesion. 

It  is  a  well-known  fact  that  by  holding  a  long  arc  with  either 
mild  steel  or  ingot  iron  electrodes,  the  rate  of  globular  transfer 
is  very  slow,  and  the  rate  of  electrode  consumption  is  decreased. 
With  a  short  arc,  on  the  other  hand,  a  slight  enlargement  of  the 
globule  brings  it  in  contact  with  the  fused  plate  where  the  forces 
of  molecular  attraction,  surface  tension,  etc.,  at  the  plate  over- 
powers these  combined  forces  to  retain  the  globule  at  the  elec- 
trode, resulting  in  its  detachment  from  the  electrode  and  solidifi- 
cation on  the  plate  material ;  there  is  then  an  attendant  increase  in 
the  rate  of  globular  transfer  and  electrode  consumption.  As  the 
above  holds  true  for  both  iron  or  mild  steel,  the  presence  of 
carbon  does  not  appear  essential  from  the  standpoint  of  metal 
transfer  for  bare  wire. 

The  hardness-  of  the  weld  will,  of  course,  be  increased  with  an 
increase  in  the  carbon  content,  and  to  a  limited  extent  the  tensile 
strength  will  be  increased,  although  practically  all  the  carbon  in 
a  mild  steel  electrode  is  lost  in  traversing  the  arc. 

Manganese. — The  per  cent  of  manganese  in  electrode  ma- 
terials varies  from  about  0.02  in  pure  ingot  iron  electrode  to  a 
ratio  of  about  three  parts  of  manganese  to  one  of  carbon  in  mild 
steel.  This  ratio  gradually  changes  as  the  carbon  is  increased 
until  in  high  carbon  steels  the  carbon  and  manganese  are  ap- 
proximately equal.  The  presence  of  manganese  between  1.5  per 
cent  and  5.5  per  cent  is  not  permissible  as  the  metal  is  very  brittle 
and  unworkable  within  this  range. 


110  ELECTRIC  ARC   WELDING 

Manganese  is  added  in  steel  to  toughen  and  improve  its  duc- 
tility. It  also  plays  the  role  of  dioxidizer  and  scavenger  when 
fused  by  ordinary  methods.  When  subjected  to  the  temperature 
and  condition  of  a  welding  arc,  however,  owing  to  the  great 
affinity  of  this  element  for  oxygen,  it  is  largely  destroyed  without 
much  effect  in  this  respect,  unless  present  in  very  large  quantities. 

Copper 

The  inclusion  of  copper  in  an  electrode  is  somewhat  rare.  It 
is  unnecessary  for  good  welding  electrodes.  However,  copper 
has  been  used  to  some  extent  with  the  view  of  resisting  corrosion, 
but  there  are  no  data  to  show  to  what  extent  this  has  been  accom- 
plished. The  copper  content  is  usually  not  specified  in  electrode 
material,  and  a  copper-plated  electrode  used  for  the  purpose  of 
introducing  copper  into  the  weld  to  prevent  corrosion,  or  to  pro- 
tect the  electrode  itself  from  becoming  rusty,  is  not  successful. 
This  type  of  electrode  when  used  will  cause  the  arc  to  be  erratic, 
and  the  copper  will  be  introduced  into  the  weld  in  lumps.  If 
copper  electrodes  are  used  the  alloy  must  be  homogeneous. 

Silicon 

A  maximum  of  0.10  per  cent  silicon  is  usually  permitted  in  elec- 
trodes. This  limit  is  not  difficult  to  meet  in  the  basic  process ; 
ordinarily,  however,  the  less  silicon  the  better.  It  has  been  ob- 
served that  an  excess  of  silicon  will  increase  the  tendency  of  the 
metal  to  boil. 

Phosphorus 

This  element  is  undesirable  in  any  quantity;  however,  0.05 
per  cent  as  a  maximum  is  permitted.  Phosphorus  causes  "cold 
short"  or  brittleness. 

Sulphur 

This  element,  like  phosphorus,  is  undesirable,  and  is  eliminated 
to  the  same  extent.  Sulphur  causes  "hot  shcyt"  or  brittleness 
when  the  metal  is  red  hot  or  hotter. 


ELECTRODE  MATERIALS  111 

Ingot  Iron  Electrodes. — There  is  in  extensive  commercial 
use  an  ingot  iron  electrode  guaranteed  to  be  99.8  per  cent  pure 
iron.  It  surpasses  the  best  Norway  or  Swedish  iron.  This  ma- 
terial is  specially  drawn  and  treated  for  arc  welding,  and  is  found 
to  work  very  satisfactorily. 

The  table  showing  the  chemical  composition  of  metal  in  elec- 
trodes indicates  that  a  common  agreement  has  not  yet  been 
reached  as  to  the  chemical  composition  of  bare  wire  electrodes 
for  welding  iron  and  soft  steel.  This  table  shows  the  composi- 
tion of  some  of  the  different  electrodes  in  use : 

CHEMICAL  COMPOSITION  OF  METAL  IN  ELECTRODES 

Per  Per  cent  Per  cent  Per  Per  Per 

Trade  name            cent  man-  phos-  cent  cent  cent 

of  electrode          carbon  ganese  phorus  sulphur  silicon  copper 

Page  steel,  "Armco 

Iron"    0.01  0.025  0.005  0.025  0.005          

Norway    0.049  0.021          0.025  0.007  0.08            

Central   steel, 

"Sweedox"    0.05  0.018  0.04  0.04  0.05            

Siemund  Wenzel 

Company    0.10  0.30  0.05  0.05  Trace         

Roebling    Company  0.13  0.47  0.025  0.025  0020 

Wilson   No.   6 0.15  0.60  0.04  0.04  Trace  0.25 

An  analysis  of  the  metal  deposited  in  a  weld  using  two  of  the 
above  electrodes  is  as  shown  in  the  following  table : 

.|,     CHEMICAL  COMPOSITION  OF  METAL  IN  WELD 

Trade  name  Percent    Percent        Percent     Percent  Percent 

of  electrode  carbon  manganese  phosphorus  sulphur  silicon 

Roebling   Company    ....  0.05  0.18  0.031  0.036  0.011 

Norway    0.05  0.018         0.020  0.015  0.011 

It  will  be  noted  that  a  large  percentage  of  the  carbon  and 
manganese  is  lost  in  passing  through  the  arc.  The  small  differ- 
ence in  the  composition  of  a  deposit  made  with  a  mild  steel  and 
an  ingot  iron  electrode  will  obviously  produce  welds  of  but  little 
difference  in  physical  quality. 

There  is  one  evident  advantage  of  the  pure  iron  material  and 
that  is  the  practical  assurance  of  freedom  from  impurities  which 
would  be  detrimental  to  the  weld  and  its  uniformity  of  composi- 
tion. Up  to  the  present  time  this  has  been  a  source  of  much 
trouble  in  the  mild  steel  material,  due  to  the  fact  that  but  very 


112  ELECTRIC  ARC   WELDING 

few  concerns  have  indicated  a  willingness  to  exercise  the  neces- 
sary care  to  make  it  uniform  for  the  present  price  and  tonnage 
demand.  This  condition  will,  of  course,  be  relieved  when  the 
supply  is  again  equal  to  the  demand.  Owing  to  the  difference 
of  opinion,  both  mild  steel  and  ingot  iron  electrode  materials  are 
used  for  the  same  class  of  work. 

A  copy  of  the  specification  No.  1,  issued  on  April  1,  1920,  by 
the  American  Welding  Society,  intended  to  govern  the  purchase 
of  electrode  materials,  follows : 

SPECIFICATIONS  FOR  BARE  IRON  AND  STEEL  ELECTRODES 

General: — 1.  The  following  specifications,  prefixed  by  the  letter  E,  are 
recommended  for  the  purchase  of  all  bare  iron  and  steel  electrodes  for 
use  in  arc  welding. 

Scope: — 2.  The  electrodes  herein  specified  are  recommended  as  cover- 
ing the  usual  railroad,   shipyard  and  industrial   requirements  as  are  al- 
lowed by  authoritative  regulating  bodies,  such  as  the  American  Bureau 
of   Shipping  and  the   Interstate   Commerce   Commission,  etc. 
Material: — 3.  Material  made  by  the  puddling  process  is  not  permitted. 
Physical    Properties: — 4.  Electrodes    shall    be    made    of    commercially 
straight  wire  of   uniform  homogeneous   structure,  free   from  irregulari- 
ties in  surface  hardness,  segregation,  oxides,  pipes,  seams,  etc.     Diameter 
shall  not  vary  more  than  plus  or  minus  3  per  cent  from  diameter  specified. 
Nomenclature: — 5.  The  use  of  the  prefix  letter  E  is  to  indicate  that  the 
materials  are  intended  for  electric  welding. 

Chemical  Composition: — 6.  Shall  be  within  the  following  limits  for  mild 
steel : 

MILD  STEEL 
No.  E  1  A 

Carbon    not  over  0.06  of  one  perr  cent 

Manganese    ' not  over  0.15  of  one  per  cent 

Phosphorus    not  over  0.04  of  one  per  cent 

Sulphur    not  over  0.04  of  one  per  cent 

Silicon    not  over  0.08  of  one  per  cent 

No.  E  1  B 

Carbon    0.13-0.18  of  one  per  cent 

Manganese    0.40-0.60  of  one  per  cent 

Phosphorus   not  over  0.04  of  one  per  cent 

Sulphur not  over  0.04  of  one  per  cent 

Silic9n    not  over  0.06  of  one  per  cent 

Recommended  Sizes: — 7.  s32  in.,  %  in.,  &  in.,  &  in.  diameters. 

Uses: — 8.  For  welding  mild  steel,  structural  shapes,  plates,  bars  or  low 
carbon  steel  forgings  and  castings. 

Note: — 9.  Under  the  heading  "Mild  Steel"  two  analyses  of  material  are 
specified,  both  of  which  are  manufactured  and  acceptable. 

^Surface  Finish: — 10.  The  surface  shall  be  smooth  and  free  from  rust, 
oil  or  grease. 

Tests: — 11.  In  the  hands  of  an  experienced  welder  electrodes  shall  dem- 
onstrate good  weldability  and  shall  pass  through  the  arc  in  flat  and 
overhead  positions  smoothly  and  evenly  without  detrimental  phenomena. 


ELECTRODE  MATERIALS  113 

Packing: — 12.  Electrodes  shall  be  delivered  in  coils  or  in  straight  14-in. 
lengths,  packed  and  wrapped  as  follows : 

(a)  Bundles  of  50  Ib.  net  weight,  securely  wired  and  wrapped  in 
heavy  weatherproof  paper. 

(b)  Bundles  of  50  Ib.  net  weight,  securely  wrapped  in  heavy  burlap. 

(c)  Boxes  or  kegs  of  100,  200  or  300  Ib.  net  weight,  and  wrapped 
as  per  paragraph  (a). 

(d)  Boxes  or  kegs  of  100,  200  or  300  Ib.  net  weight,  and  wrapped 
as  per  paragraph   (b). 

(e)  Coils  of  approximately  50  or  100  Ib.  net  weight,  and  wrapped 
as  per  paragraph   (a)    or   (b). 

Marking: — 13.  All  bundles,  coils,  boxes  or  kegs  shall  be  provided  with 
a  metal  tag  wired  or  nailed  on  the  outside,  bearing  the  following 
information: 

Make 

Specif.  No 

Dia 

Nom.  weight 

Ordering: — 14.  Material  ordered  under  these  specifications  shall  be 
known  as : 

"Electrodes,    iron    and    steel,    bare"    American    Welding 
Society    Specifications    No.     1,    issued    April    1,     1920. 
All  orders  should  be  specified  in  pounds. 
In  addition,  requisitions  shall  show  the  following: 
Specif.  No. 
Size 
Packinn 

State  of  Existence  of  Metal  in  Arc. — In  a  previous  section  it 
was  stated  that  the  metal,  when  passing  through  the  arc,  accord- 
ing to  all  evidence  was  in  the  form  of  vapor  and  minute  globules. 
This  contention  has  been  supported  by  Mr.  Hudson  in  the  Journal 
of  the  American  Welding  Society.  Mr.  Hudson,  after  extensive 
research,  states  that  "it  would  appear  from  observed  facts  that 
the  metal  deposited  during  metallic  arc  welding  is  transmitted,  in 
part  at  least,  in  the  form  of  minute  particles  at  the  rate  of  ap- 
proximately 50  per  second,  and  these  are  projected  from  the  elec- 
trode globule  by  the  internal  expansion  of  some  vapor,  possibly  con- 
sisting partly  of  carbon  monoxide  gas.  The  expelled  particles  pass 
too'  rapidly  through  the  arc  to  become  vaporized  and  reach  the 
plate  in  a  fluid  state." 

The  rate  of  flow  of  the  expelled  particles  referred  to  here  was 
determined  by  holding  an  incandescent  electrode,  just  removed 
from  ordinary  welding,  over  the  rim  of  a  revolving  iron  wheel. 
Furthermore,  the  arc  tends  to  be  established  from  whichever 
portion  of  the  work  or  electrode  volatilizes  most  rapidly.  In  this 
connection  Mr.  Hudson  states  that,  "since  the  melting  points  of 


114  ELECTRIC  ARC   WELDING 

the  different  elements  usually  present  in  electrode  materials,  and 
other  thermal  constants  of  these  elements  and  their  compounds 
vary  widely,  and  their  chemical  affinities  are  quite  different,  it  is 
to  be  expected  that  the  constituents  of  an  electrode  subjected  to 
a  high  temperature  will  change  from  solid  to  liquid  or  gaseous 
form  successively  and  not  at  the  same  instant.  Since  the  melting 
point  of  iron  is  higher  than  that  of  any  other  constituent  of  an 
electrode,  with  the  exception  of  carbon,  which  combines  rapidly 
with  the  oxygen  (present  in  the  air)  at  welding  temperatures  to 
form  carbon  monoxide,  it  is  furthermore  to  be  expected  that  in 
the  welding  process,  the  iron  constituent  will  melt  last. 

"In  metallic  arc  welding  the  temperature  changes  which  take 
place  differ  to  a  marked  degree  from  the  changes  incident  to  the 
usual  methods  of  heating  metals,  to  the  extent  that  in  welding  a 
small  mass'  of  the  electrode  is  subjected  to  a  high  temperature 
for  a  very  short  interval  of  time.  The  distinctive  thermal  feature 
of  metallic  arc  welding  is  the  sudden  rise  and  fall  of  temperature 
in  the  metal  transmitted  to  the  work. 

"Under  these  circumstances  it  may  be  seen  that  the  melting  of 
the  iron  is  delayed  by  the  heat  absorbed  by  the  other  constituents 
of  the  electrode,  and  this  fact,  together  with  the  limited  time  of 
application  of  high  temperature,  disproves  the  possibility  that  the 
iron  is  completely  vaporized  in  the  welding  process." 

The  small  spherical  particles  found  about  a  weld  are  thought 
to  be  those  particles  which  strike  unfused  metal  on  the  work,  and 
bounce  along  the  surface.  The  gray  dust  seen  floating  in  the  air, 
and  which  collects  around  the  weld,  is  thought  to  be,  partly  at 
least,  the  vapor  carried  out  of  the  arc  with  these  particles.  These 
losses  are  accentuated  with  poor  welding  electrodes  and  may 
constitute  a  loss  of  14  per  cent  of  the  electrode  material  con- 
sumed. 

An  examination  of  an  electrode  which  does  not  work  smoothly 
will  usually  show  that  the  fused  end  is  enlarged.  This  may  be 
accounted  for  by  the  fact  that  most  materials  will  show  a  marked 
increase  in  volume  with  an  increase  of  temperature.  An  electrode 
fused  by  an  excessive  arc  length  will  also  show  an  enlargement  at 
the  end  of  the  electrode. 

From  the  foregoing  it  would  seem  that  some  elements  alloyed 


ELECTRODE  MATERIALS  115 

with  the  iron  or  steel  may  be  beneficial  to  the  smooth  working  of 
an  electrode,  whereas  others  may  not.  At  the  present  time  there 
does  not  seem  to  be  an  electrode  on  the  market  containing  a 
composition  which  will  materially  improve  its  working  quality  for 
bare  wire  welding. 

An  examination  of  the  fused  end  of  a  smooth  working  elec- 
trode will  present  a  cup-shaped  appearance  which  would  indicate 
that  the  center  or  core  fused  first  and  the  shell  last.  An  ideal 
electrode,  therefore,  would  seem  to  be  one  having  a  high-fusing- 
point  shell,  graduated  to  a  lower-melting-point  core.  'Many  meth- 
ods have  been  employed  to  produce  this  effect,  and  while  there  are 
a  number  of  treatments,  usually  confined  to  the  surface,  which 
work  after  a  fashion,  many  of  them  are  incidentally  detrimental 
in  other  ways,  such  as  increasing  the  slag  inclusions  in  the  weld, 
etc.  A  method  of  heat  treatment  and  drawing  the  electrode  ma- 
terial so  as  to  produce  a  shell  having  a  high  melting  point  and  a 
core  having  a  low  melting  point  is  employed  at  least  by  one  con- 
cern. This  seems  to  be  an  ideal  method,  as  undesirable  surface 
finishes  are  eliminated. 

Physical  Properties  of  Bare  Wire  Electrodes. — The  physical 
properties  of  electrode  material  are  of  extreme  importance  to  its 
smooth  working  quality.  The  structure  must  be  uniformly  homo- 
geneous, free  from  any  structural  imperfections  such  as  oxides, 
pipes,  seams,  etc.  The  materials  from  which  the  wire  is  manu- 
factured should  be  made  by  the  best  approved  process,  open 
hearth  or  electric  furnace. 

At  the  present  time  about  the  only  sure  check  the  purchaser 
of  electrodes  has  on  their  weldability  is  through  actual  test  by  an 
experienced  operator,  who  shall  demonstrate  whether  or  not  the 
material  flows  smoothly  and  in  a  reasonably  uniform,  finely 
divided  state  without  any  detrimental  effects.  The  general  use 
of  coatings  to  make  an  inferior  electrode  flow  smoothly  is  not 
considered  good  practice.  In  some  cases  poor  welding  material, 
termed  "wild  iron,"  may  not  necessarily  be  inferior  for  such 
purposes  when  a  coating  is  applied  to  quiet  the  arc  and  prevent 
sputtering.  In  most  cases,  however,  this  method  is  grossly  mis- 
used by  applying  a  coating  to  electrodes  having  excessive  amounts 
of  impurities,  producing  results  detrimental  to  the  weld. 


116  ELECTRIC  ARC   WELDING 

From  the  foregoing  it  is  evident  that  the  electrode  material  for 
bare  wire  welding  calls  for  either  a  practically  pure  iron  electrode 
or  for  what  is  essentially  a  basic  mild  steel  electrode  with  the  im- 
purities not  exceeding  those  enumerated,  and  specially  treated  to 
meet  the  requirements.  It  is  also  evident  that  metal  deposited 
with  a  bare  electrode  is  practically,  free  from  carbon  or  man- 
ganese, and,  as  the  fusion  of  metals  under  the  conditions  of  the 
welding  process  makes  for  brittleness,  the  ductility  of  the  weld  is 
greatly  impaired.  This  latter  deficiency  has  proved  to  be  a  serious 
obstacle  in  the  application  of  the  process  to  some  structural  and 
machine  members  subjected  to  repeated  stresses,  such  as  bridge 
cord  members,  ship  hulls,  car  axles,  piston  rods,  etc. 

The  loss  of  the  constituents  of  the  electrode  in  bare  wire  weld- 
ing prevents  the  use  of  certain  alloys  such  as  carbon,  manganese, 
nickel,  vanadium,  etc.,  to  any  appreciable  extent.  These  are  often 
added  to  secure  strength  and  toughness,  or  to  limit  abrasive  wear, 
and  are  needed  in  many  instances. 

The  tensile  strength  of  welds  made  with  bare  electrodes  is 
fairly  satisfactory,  as  indicated  by  the  many  tests  which  have  been 
conducted.  In  practically  every  case  the  average  tensile  strength 
was  50,000  Ib.  per  sq.  in.  It  is  therefore  evident  that  if  the  con- 
ditions under  which  welds  are  made  are  improved  so  as  to  secure 
more  ductile  metal  in  the  weld  and  in  some  cases  certain  alloys 
as  mentioned  above,  the  scope  of  application  of  the  welding 
process  will  be  practically  unlimited.  The  need  of  such  improve- 
ments is  indicated  by  the  research  and  development  work  now 
being  carried  on  in  this  country  as  well  as  abroad. 

Covered  Electrodes  for  Arc  Welding. — A  covered  electrode, 
or  "flux  covered"  as  it  is  sometimes  called,  is  manufactured  by 
the  Quasi  Arc  Weltrode  Company  of  England.  This  electrode  is 
a  metallic  rod  or  wire  with  a  covering  of  blue  asbestos  yarn, 
sometimes  accompanied  with  other  coatings  of  ferrous  silicate, 
which,  on  fusing,  is  claimed  to  surround  the  metal  with  an  inert 
gas,  and  prevent  oxidation  of  the  deposited  metal.  The  yarn, 
it  is  claimed,  is  coated  with  sodium  silicate,  aluminum  silicate  or  a 
similar  compound  to  vary  the  fusing  temperature,  of  the  asbestos. 
Another  claim  for  this  electrode  is  that  the  covering  forms  a 
fusible  insulating  coating  around  the  metal  core  of  sufficient  thick- 


ELECTRODE  MATERIALS  117 

ness  so  that  it  may  be  held  at  an  angle  and  resting  on  the  work 
permitting  the  electrode  to  feed  itself.  In  addition  to  the  cover- 
ing an  aluminum  wire  is  placed  between  it  and  the  core  for  the 
purpose  of  preventing  oxidation.  When  aluminum  is  present  in 
a  molten  mass  of  iron,  all  of  the  aluminum  will  be  oxidized 
before  any  of  the  iron  is  attached,  since  aluminum  has  a  greater 
affinity  for  oxygen  than  iron. 

The  covered  electrode  is  used  extensively  in  England,  mostly  in 
connection  with  alternating  current.  When  used  with  direct  cur- 
rent the  polarity  is  opposite  to  that  ordinarily  used  for  bare  elec- 
trode welding ;  that  is,  the  electrode  is  made  the  positive  pole  and 
the  work  the  negative  pole.  An  exhaustive  series  of  tests  has 
been  made  to  investigate  the  claims  of  this  electrode,  but  the 
results  have  not  yet  been  published. 

The  cost  of  marketing  the  covered  type  of  electrode  seems  to 
have  limited  its  use  in  this  country;  also  the  somewhat  different 
methods  of  application  necessitated  by  its  use  and  the  removing 
of  the  heavy  scale  formed  on  the  weld  have  given  rise  to  some 
objections.  The  metal  expelled  from  the  electrode  becomes  ex- 
tremely fluid,  and  remains  in  that  state  for  a  longer  period  than 
in  the  case  of  a  bare  electrode,  due  to  the  heavy  slag  formed  over 
the  weld.  For  this  reason  its  use  on  work  other  than  practically 
flat  or  down-hand  welding  is  more  or  less  difficult.  Special  elec- 
trodes are  said  to  be  furnished  by  this  company  for  vertical  and 
overhead  welding,  also  electrodes  of  special  composition. 

Test  data  to  show  the  percentage  of  different  alloy  constituents 
that  can  be  deposited  in  the  weld  by  the  covered  electrode  are  not 
available.  It  has  been  demonstrated,  however,  that  a  weld  made 
by  a  mild-steel-covered  electrode  is  softer  and  more  ductile  than 
that  made  with  a  bare  electrode.  It  is  understood  that  the  use  of 
this  covered  electrode  in  ship  construction  in  England  has  been 
approved  by  Lloyds  Insurance  Company. 

Coated  Electrode  for  Arc  Welding. — The  term  coated  elec- 
trode has  in  the  past  been  taken  literally  to  refer  to  some  form  of 
a  flux  applied  to  the  surface  of  the  electrode,  the  function  of 
which  was  to  fuse  with  the  electrode  and  act  purely  as  a  cleanser. 
As  a  matter  of  fact,  however,  there  is  at  least  one  "coated"  elec- 


118  ELECTRIC  ARC   WELDING 

trode,  not  necessarily  flux  coated,  in  commercial  use,  which  per- 
forms practically  all  of  the  functions  claimed  for  the  heavy 
"covered"  electrode. 

The  coating  is  composed  of  a  high-fusion-point  material,  or 
materials  mixed  with  a  suitable  liquid  also  of  a  high  fusion  point, 
which  on  drying  serves  as  a  binder  to  hold  the  material  firmly  to 
the  surface  of  the  electrode.  The  thickness  of  the  coating,  as 
compared  to  the  covered  electrode,  is  thin.  The  welding  is  per- 
formed in  the  same  general  way  as  with  a  bare  electrode ;  that  is, 
the  arc  is  established  and  manipulated  by  the  operator,  and  the 
coating  is  not  used  to  separate  the  end  of  the  electrode  the  proper 
distance  from  the  work.  The  iron  or  mild-steel  coated  electrode 
can  be  used  in  a  vertical,  horizontal  or  overhead  position  without 
difficulty.  Electrodes  having  high  percentages  of  alloys  are  con- 
fined to  practically  down-hand  welding,  but  generally  this  class 
of  work  is  not  required  to  be  done  in  other  positions. 

The  coating  on  the  electrode  fuses  at  practically  the  same  rate 
as  the  electrode.  Its  function  is  to  remain  in  a  fluid  condition 
about  the  particles  or  globules  as  they  are  rapidly  expelled  from 
the  end  of  the  electrode  and  arrange  itself  over  the  surface  of  the 
deposited  metal,  thus  forming  an  almost  continuous  sheath  or 
miniature  crucible  about  the  metal  when  undergoing  the  changes 
from  a  solid  to  a  liquid  or  a  gaseous  state,  or  vice  versa,  confining 
the  arc  gases  and  excluding  to  a  very  large  extent  the  surrounding 
air,  thus  securing  a  more  ductile  weld  by  preventing  to  a  great 
extent  the  effects  of  nitrogen  and  oxygen. 

The  effectiveness  of  the  coating  is  evidenced  by  the  fact  that  a 
high  manganese  and  carbon  content  can  be  deposited  in  the  weld. 
This  is  shown  by  the  following  test :  The  metal  from  an  elec- 
trode containing  0.99  per  cent  carbon  and "10.50  per  cent  man- 
ganese, with  a  coating  as  mentioned  above,  was  deposited  on  a 
carbon  steel  rail  by  metallic  arc  welding.  Direct  current  was 
used,  with  the  work  positive  and  the  electrode  negative.  The 
appearance  of  the  finished  weld  was  perfect,  being  smooth  and 
without  gas  holes  or  other  imperfections.  Further  examination 
showed  that  the  union  was  perfect.  An  analysis  of  the  electrode 
and  the  deposited  metal  is  shown  in  the  table. 


ELECTRODE  MATERIALS  119 

Electrode,  Deposited  metal, 
Element                                        per  cent  per  cent 

Carbon    0.99  0.71 

Phosphorus    0.043  0.061 

Sulphur   0.022  0.018 

Manganese   10.51  10.19 

The  Brinnell  hardness  of  the  head  of  the  rail  was  154,  and  the 
average  hardness  of  the  deposited  metal  was  156.  Due  to  the 
extreme  toughness  of  the  metal  much  trouble  was  experienced  in 
pulverizing  the  deposit  for  analysis;  many  tools  were  broken, 
and  when  the  sample  was  finally  placed  under  a  steam  hammer  in 
an  effort  to  break  it  up,  deep  impressions  were  made  in  the  ham- 
mer jaws. 

Another  test  was  conducted  to  determine  the  loss  of  constitu- 
ents, using  electrodes  containing  alloys  in  a  milder  form,  and  with 
a  very  thin  coating  such  as  would  permit  welding  in  a  vertical 
or  horizontal  position.  The  results  are  given  in  the  following 
table : 

Electrode,  Deposited  metal, 

Element  per  cent  per  cent 

Carbon   0.18  0.15 

Manganese   0.50  0.40 

Phosphorus    0.012  0.012 

Sulphur 0.032  0.032 

Silicon    0.140  0.12 

Nickel  2.97  2.08 

Ordinary  physical  tests  of  welds  made  with  the  coated  elec- 
trodes showed  an  increased  ductility  over  those  made  with  the 
same  material  without  the  coating. 

In  the  past  too  much  reliance  has  been  placed  upon  figures  of 
tensile  strength.  Many  welds  having  fair  tensile  strength  are,  on 
the  other  hand,  weak  in  transverse  strength. 

The  superiority  of  coated  electrode  welds  has  been  demon- 
strated in  many  instances  in  practice,  where  they  have  been  in 
use  for  about  18  months.  Incidental  advantages  have  been 
noticed  with  the  coated  electrode  that  may  be  of  interest.  The 
lack  of  uniformity  in  the  ordinary  welding  wire  has  always  been 
a  very  serious  matter,  and  even  with  material  made  in  the  most 
careful  manner  there  will  be  found  some  electrodes  that  do  not 
work  well. 

When  the  electrodes  are  coated,  imperfections  in  the  wire  may 


120  ELECTRIC  ARC   WELDING 

not  be  noticed ;  as  a  result,  material  is  sometimes  used  which 
would  otherwise  be  discarded.  In  this  connection  it  should  be 
understood  that  it  is  not  intended  to  infer  that  an  inferior  elec- 
trode, especially  in  regard  to  the  composition,  can  be  made  suit- 
able for  welding  by  coating  it.  As  a  matter  of  fact,  it  is  just  as 
important  that  coated  electrodes  be  of  the  proper  quality  as  it  is 
for  bare  electrodes.  It  would  be  better  to  tolerate  non-uni- 
formity than  to  deposit  metal  with  excessive  constituents  which 
are  detrimental  to  the  weld. 

Operators  using  coated  electrodes  contend  that  the  personal 
efforts  of  welding  are  somewhat  minimized  when  the  electrode  is 
coated.  Another  apparent  advantage  of  the  coated  electrode  is 
that  it  provides  a  scale  for  the  weld,  which,  when  the  coating  has 
the  right  composition,  has  a  greater  co-efficient  of  contraction 
than  the  weld,  so  that  when  the  weld  cools  somewhat  the  scale 
may  be  readily  removed  by  light  tapping  with  a  hammer  or  chisel, 
thus  exposing  perfectly  clean  metal  preparatory  to  adding  the 
next  layer  of  metal.  The  scale,  by  excluding  the  air,  also  pro- 
longs the  cooling  so  that  the  temperature  of  the  weld  is  not 
reduced  so  rapidly.  Consequently,  the  weld  does  not  tend  to 
become  brittle  to  the  same  extent  as  welds  made  with  bare  elec- 
trodes. 

The  composition  of  the  metal  in  the  electrode,  in  relation  to  the 
part  to  be  welded,  is  obviously  a  matter  of  importance.  What 
this  composition  is  to  be  can  only  be  gaged  by  experiment  and 
by  wide  experience.  The  complexities  encountered  in  performing 
welding  by  the  electric  arc  are  so  different  from  those  of  other 
methods  of  heating  metals,  that  few  data  are  available  upon 
which  judgment  may  be  based.  In  view  of  such  conditions  many 
difficulties  arise  in  devising  tests  to*  determine  the  quality  of  an 
electrode. 

Procedure  for  Testing  Electrodes  for  Arc  Welding. — A 
standard  procedure  of  testing  welds  to  determine  the  relative 
merits  of  different  electrodes  was  drafted  by  the  welding  com- 
mittee of  the  Emergency  Fleet  Corporation.  Many  elements 
enter  into  a  test  of  this  nature,  so  that  if  the  proper  consideration 
is  not  given  to  each  they  will  greatly  affect  the  accuracy  of  the 
ultimate  result.  An  abstract  of  this  specification  with  slight 
variations  follows: 


ELECTRODE  MATERIALS 


121 


This  specification  describes  a  test  of  electrodes  and  not  a  combination 
of  an  electrode  and  of  an  apparatus  (or  welding  equipment).  The  sys- 
tem used  in  making  such  tests  may  or  may  not  prove  to  be  of  importance. 

It  is  sought  to  minimize  the  influence  of  the  individuality  of  the 
operator  by  requiring  the  test  to  include  welds  made  by  at  least  two 
operators.  Only  operators  known  to  be  competent  should  be  used  for 
such  tests,  and  the  approving  and  certifying  of  operators  would  be  within 
the  province  of  the  purchaser,  as  well  as  the  approving  and  certifying  of 
systems. 

Sample  Electrodes. — Sample  electrodes  should  be  accompanied  by  affi- 
davits giving  the  trade-name  under  which  the  electrode  is  marketed, 


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FIG.  50  —  Test  Pieces  for  Tensile,  Cold  Bend  and  Fatigue  Specimens 

together  with  certification  that  all  electrodes  bearing  this  trade-name  will 
be  substantially  the  same  as  the  sample  submitted,  and  such  other  infor- 
mation as  is  deemed  necessary  by  the  purchaser. 

Plate  Material.  —  Standard  %  in.  ship-plate,  as  adopted  by  the  American 
Society  of  Testing  Materials,  A  12-16  (page  98,  A.  S.  T.  M.  Standards, 
1918),  are  specified  for  the  test. 

The  plates  from  which  tensile,  cold-bend  and  fatigue  specimens  are 
to  be  made  shall  be  cut  into  pieces  9  in.  by  30  in.,  as  shown  in  Fig.  50. 

The  plates  from  which  impact  specimens  are  to  be  made  shall  be  cut 
into  pieces  30  in.  by  30  in.,  as  shown  in  Fig.  51. 

Number  of  Test  Welds.  —  One  30  in.  weld  for  the  tensile,  cold-bend 
and  fatigue  test  shall  be  made,  as  indicated  in  Fig.  50. 

Three  30  in.  test  welds  for  the  impact  test  shall  be  made,  as  indicated 
in  Fig.  51. 

Preparation  of  Plates  for  Physical  Test.  —  (a)  Each  test  weld  shall 
be  machined  down  on  both  sides  to  about  the  surface  of  the  plate. 

(b)  Specimens  shall  be  cut  from  each  test  weld  reserved  for  physical 
tests,  as  follows: 

1.  Three  tensile  specimens  —  these  shall  be  machined  to  a  uniform  width 
of  1^  in.  unless  a  weld  of  great  strength  makes  it  necessary  to  leave 
shoulders  at  the  ends,  in  which  case  the  standard  A.  S.  T.  M.  test  speci- 
mens for  sheet  iron  and  steel  shall  be  prepared. 


122 


ELECTRIC  ARC   WELDING 


2.  Three  cold-bend  specimens — these  shall  be  machined  to  a  uniform 
width  of  \Vz  in. 

3.  Six    fatigue    specimens— these    shall    be    machined    to    about    y^    in. 
diameter  and  10  in.  long.     (The  exact  dimensions  are  to  be  determined 
by  experiment.) 

Physical  Tests. —  (a)  Tensile  Strength.  The  three  specimens  shall  be 
tested  in  accordance  with  the  practice  recommended  by  the  A.  S.  T.  M. 
and  shall  include  the  determination  of  the  tensile  strength,  yield  point 
(by  drop-of-beam  method),  reduction  of  area  and  total  elongation  after 
rupture  in  2  in.  and  8  in. 

(b)   Cold-bend  Test. — This  test  shall  be  made  by  placing  the  specimen 


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FIG.  51 — Test  Pieces  for  Impact  Specimens 


on  two  ball-bearing  rollers  with  the  apex  of  the  "V"  upward  and  mid- 
way between  the  rollers  and  loaded  at  the  center  of  thje  span  thus 
formed  by  a  cylindrical  surface  having  a  diameter  of  \Vz  in.  This 
surface  shall  bend  the  specimen  downward  between  the  rollers  until  a 
fracture  appears  on  the  lower  side  of  the  specimen.  The  loading  shall 
then  be  stopped  and  the  angle  noted  through  which  the  specimen  has 
been  bent. 

(c)  Fatigue    Test — Each   of    the   six    specimens    shall    be   tested    in    a 
special  rotating  type  of  machine  similar  to  that  used  by  Lloyd's  Register 
of  Shipping.     (Exact  details  to  be  determined  by  experiment.) 

(d)  Impact  Test. — Each  impact  test  specimen  shall  be  placed  on  sup- 
ports 18  in.  high  and  4Vz   ft.  apart.     A  spherical  weight  of  500  Ib.  shall 
be  allowed  to  fall  freely  through  a  distance  of  10  ft.,  striking  the  weld, 
which  shall  be  at  the  center  of  the  span.     The  apex  of  the  "V"  shall 
be  upward. 

(e)  Test  of  Original  Plate. — In  order  to  establish  the  physical  prop- 
erties of  the  unwelded  plate,  tensile,   cold-bend  and   fatigue  tests   shall 
be  made  on  a  sample  selected  at  random  from  the  pieces  used  for  the 
test  welds,  but  before  such  welds  are  made. 

Chemical  Analysis. — A  chemical  analysis  shall  be  made  of: 


ELECTRODE  MATERIALS  123 

(a)  The  original  plate  in  one  test-weld  selected  at  random. 

(b)  The  metal  at  the  center  of  one  test-weld  selected  at  random. 
Photomicrographs. — Photomicrographs  shall  be  made  of  one  specimen 

v/eld  selected  at  random,  as  follows : 

At  center  of  weld ;  at  juncture  of  weld  and  original  metal ;  in  ad- 
jacent original  metal;  cross-section  of  electrode;  longitudinal  section 
of  electrode. 

Any  information  on  welding  data  which  might  be  of  importance  should 
be  recorded  by  the  authorized  representatives  during  the  welding  opera- 
tions, such  as  identification  mark  of  electrodes,  description  of  electrode, 
sufficient  description  of  welding  apparatus  for  identification,  name  of 
operator,  kind  of  current  (i.  e.,  d.  c.  or  a.  c.),  open  circuit  voltage,  arc 
current  and  voltage  across  arc,  working  quality  of  electrode,  giving  exact 
description  of  peculiarities  noticed,  if  any,  time  per  weld,  weight  of 
electrodes  consumed,  and  any  other  information  which  will  assist  in 
determining  the  performance  of  the  electrode  or  the  quality  of  the  weld. 

A  test,  such  as  outlined,  will  involve  some  expense,  but  the 
resultant  data  and  information  revealed  will  constitute  a  wealth 
of  information  which  will  offset  the  expenditure  many  times. 
The  adaptation  of  a  standard  form  of  procedure  for  testing 
welding  electrodes  will  at  least  result  in  the  elimination  of  much 
of  the  inferior  material  now  in  existence,  and  it  is  hoped  it  will  be 
an  incentive  to  further  the  development  of  electrodes  by  the 
manufacturer.  The  lack  of  uniformly  dependable  ekctrodes  has 
always  been  a  serious  obstacle  in  the  progress  of  arc  welding,  and 
with  improvements  in  this  phase  of  the  art  great  extensions  in  its 
application  will  result. 

Cast  Iron  Electrodes  for  Arc  Welding. — Due  to  the  non- 
homogeneous  structure  of  cast  iron,  and  to  the  behavior  of  a 
material  of  this  composition  and  the  conditions  of  arc  welding, 
its  use  has  not  been  successful  for  metallic  welding.  Experiments 
by  different  parties  are  now  under  way,  using  cast  iron  rods  high 
in  silicon,  ingot  iron  high  in  silicon,  bronzes,  etc.,  which  may 
result  in  more  satisfactory  results  in  cast  iron  welding. 

Non-Ferrous  Electrodes  for  Arc  Welding. — Up  to  the  pres- 
ent time  no  great  amount  of  research  has  been  made  of  non- 
ferrous  electrodes.  Certain  aluminum-bronze  alloy  electrodes, 
low  in  zinc,  are  used  with  satisfactory  results.  The  presence  of 
more  than  3  per  cent  of  zinc  is  known  to  be  unsatisfactory,  as  this 
element  vaporizes  at  a  much  lower  temperature  than  the  other 
constituents  with  which  it  is  alloyed.  Some  experiments  that 
have  been  made  indicate  that  non-ferrous  electrodes  properly 
made  can  be  used,  especially  if  they  are  coated  or  flux  covered. 


124 


ELECTRIC  ARC   WELDING 


Carbon  Electrodes  for  Arc  Welding. — Carbon  electrodes  are 
furnished  in  various  diameters,  ranging  from  3/16  in.  to  2  in. 
Various  compositions  are  furnished  to  vary  the  conductivity  of 
the  rod.  They  are  also  furnished  plain  and  copper  coated.  The 


600 


soo 


£.400 


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Grahite/ 


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andSpec/a/_ 
Graph) fe 


300 


200 


100 


3      !,  3"  f  s  3  i 

Te     4  8  2  8  4  Q 

Diameter  in  Inches. 

FIG.  52 — Current  Carrying  Capacity  of  Welding  Carbons 

usual  length  is  12  in.  and  they  are  always  pointed  at  the  arc  end, 
and  in  some  cases  the  entire  electrode  is  tapered.  The  approxi- 
mate current  carrying  capacity  for  different  sizes  and  grades  of 
carbon  electrodes  is  shown  in  Fig.  52,  and  may  assist  the  user  in 
selecting  the  proper  size  and  grade  of  electrode  to  best  suit  the 
work  at  hand. 


VIII 
PREPARING  WORK  FOR  ELECTRIC  ARC  WELDING 

In  detail,  the  preparation  of  work  to  be  welded  varies  with  the 
characteristics  of  the  metal,  the  thickness  of  the  parts  to  be 
welded  and,  most  of  all,  the  form  and  position  of  these  parts. 
However,  general  rules  serve  to  indicate  the  methods  to  be  ap- 
plied in  each  particular  case.  When  the  material  to  be  welded 
is  prepared  properly  the  job  is  half  done,  because  the  execution 
of  the  actual  welding  process  depends  in  a  large  measure  on  the 
accessibility  provided  for  the  operator,  such  as  the  arrangement 
and  preparation  of  the  parts  to  be  joined.  The  methods  used  for 
welds  of  various  kinds  are  described  in  this  article,  but  the  fol- 
lowing information  concerning  the  preparation  of  the  parts  may 
be  of  value  in  a  general  way: 

(1)  Expansion  and  contraction  should  be  provided  for  when 
it  is  possible  to  do  so,  otherwise  the  effective  strength  may  be 
materially  reduced  or  the  work  left  in  a  distorted  or  warped 
condition.   ^ 

(2)  Accessibility  for  the  operator  should  be  provided  for  in 
order  to   simplify  the  execution  of  the  welding  process.     The 
work  or  the  position  of  the  parts  to  be  welded  should  be  arranged 
so  as  to  be  the  least  difficult  for  the  operator  to  get  at.     Good 
welding  can  be  done  in  an  overhead  position,  but  other  positions 
require   less   effort   and  the   probabilities   for   a  good   weld   are 
greater. 

Proper  beveling  and  spacing  of  parts,  to  insure  uniform  fusion 
throughout  the  thickness  of  the  parts  to  be  joined,  will  also 
determine  to  a  large  degree  the  ultimate  strength  of  the  weld. 

(3)  It  is  necessary  to  know  what  the  service  requirements  of 
the  parts  will  be  in  order  to  make  a  study  of  the  stresses  to  which 
the  work  will  be  subjected,  to  determine  the  kind  of  weld  that 
should  be  made.    Different  kinds  of  welds  will  be  required.    The 

125 


126  ELECTRIC  ARC   WELDING 

kind  to  be  used  will  depend  upon  whether  the  strain  is  great, 
small,  direct  tension,  bending,  torsion,  prying,  compressive,  or  a 
combination  of  these. 

(4)  The  cleaning  of  the  surfaces  on  which  fusion  takes  place 
must  never  be  lost  sight  of.  According  to  the  surface  of  the 
metal,  this  mechanical  cleaning  may  be  done  with  hammer  and 
chisel,  wire  brush,  roughing  tool,  sand  blast,  emery  wheel,  file  or  a 
combination  thereof.  The  use  of  chemical  agents  to  slag  the 
oxides  from  the  surface  of  the  work  during  welding  is  not 
strongly  recommended  for  arc  welding.  Mechanical  methods  of 
cleaning  are  preferable. 

Expansion  and  Contraction  Require  Precautionary  Meas- 
ures.— Attention  has  been  drawn  to  the  importance  of  expan- 
sion and  contraction  in  the  case  of  autogenous  welding.  How- 
ever, as  the  preparation  and  arrangement  of  parts  to  be  welded 
are  governed  largely  by  this  phenomenon,  it  is  necessary  to  refer 
further  to  this  subject. 

It  must  be  understood  that  expansion  and  contraction  cannot 
be  overcome  by  force,  and  it  is  useless  to  try  to  oppose  them.  We 
may  only  hope  to  avoid  or  limit  their  consequences.  Also,  it  must 
be  remembered  that  a  given  volume  of  metal  occupies  more  space 
when  in  a  heated  or  molten  state  than  when  in  a  cool  normal 
condition.  For  example :  Two  bars,  such  as  shown  in  Fig.  53, 
are  to  be  joined  by  the  addition  of  molten  metal  between  them. 
No  bad  effects  of  expansion  and  contraction  are  to  be  feared  in 
this  case  because  the  opening  is  uniform  and  the  parts  are  free  to 
expand  or  contract. 

However,  if  two  plates,  such  as  shown  in  Fig.  54,  with  beveled 
edges  are  to  be  joined  the  situation  is  different.  To  begin  with, 
the  plates  are  horizontal;  but  when  the  weld  is  completed  their 
relative  positions  will  have  changed  as  shown  (exaggerated)  in 
Fig.  55  provided  they  are  free  to  move.  This  is  due  to  the  differ- 
ence in  the  openings  at  points  A  and  B;  that  is,  the  amount  of  hot 
expanded  metal  added  between  points  at  A  (to  contract  on  cool- 
ing) is  smaller  than  that  between  points  at  B;  consequently  con- 
traction is  greater  at  point  B. 

No  bad  effects  of  expansion  need  be  feared,  since  on  heating  or 
fusion  the  beveled  edges  expand  and  the  parts  to  be  welded  ap- 


PREPARATION  OF  WORK 


127 


proach  each  other.  Also,  the  tendency  for  expansion  is  reduced 
to  almost  nothing  in  the  case  of  metallic  arc  welding  because  of 
the  extreme  localization  of  the  arc's  heat.  Distortion  may  be  al- 
lowed for  by  adjustment  of  parts  before  the  welding  begins,  so 
that  when  contraction  occurs  the  united  plates  will  form  a  flat 
surface. 

In  welding  long  butt  seams  of  medium  thickness,  in  addition  to 
the  tendency  for  distortion  above-mentioned,  the  contraction  of 


FIGS.   53  to  57 — Parts  to  be  Joined   Showing  Effect   of   Expansion  and 

Contraction 

the  weld  will  cause  the  edges  to  approach  each  other  as  the  weld- 
ing progresses.  When  it  is  possible  to  do  so  this  condition  should 
be  allowed  for.;  by  separating  the  edges  of  the  plates  more  at  the 
end  toward  which  the  welding  is  to  progress  than  where  the 
welding  is  to  start,  as  shown  in  Fig.  56.  The  amount  of  allow- 
ance for  this  contraction  varies  slightly  with  the  speed  at  which 
the  work  is  done  and  the  mass  and  shape  of  the  parts.  It  will 
usually  vary  from  one  to  two  per  cent  of  the  length  of  the  weld. 
These  figures  are  approximate.  The  operator  will  find  the  exact 
spacing  required,  depending  upon  conditions,  after  he  has  had 
some  experience  with  welding  of  this  character.  He  can  correct 
a  slight  mistake  in  spacing  by  varying  the  speed  of  his  work ;  that 
is,  if  it  tends  to  close  too  quickly  the  work  should  be  hurried,  and 
if  it  does  not  close  quickly  enough  the  work  should  be  prolonged. 
Closing  of  the  edges  and  warping  may  be  prevented  in  some 
cases  by  clamping  or  tack  welding  to  compel  a  slight  giving  of  the 


128  ELECTRIC  ARC   WELDING 

metal  on  cooling  and  contracting.  This,  however,  is  not  the  best 
practice,  especially  with  lighter  material  where  the  parts  being 
welded  become  very  hot;  but  it  is  practiced  to  a  great  extent  on 
heavy  work,  and  if  the  metal  in  the  weld  is  ductile  the  contraction 
will  not  produce  breaks  or  even  serious  strains.  An  example  of 
this  is  illustrated  in  Fig.  57  in  the  welding  of  locomotive  frames, 
where  it  is  very  seldom  that  any  allowances  are  made  for  contrac- 
tion; yet  many  such  frames  have  been  welded  successfully. 

Even  though  the  members  of  heavy  parts  are  free  to  move, 
there  should  be  very  little  distortion  in  the  case  of  metallic  arc 
welding,  as  contraction  will  have  occurred  where  the  welding  was 
started  long  before  the  weld  can  be  completed.  Pre-heating  may 
be  employed  in  certain  cases,  but  it  is  not  used  to  as  great  an 
extent  with  metallic  arc  welding  as  it  is  with  oxy-acetylene  weld- 
ing, since  the  area  heated  by  the  electric  process  is  comparatively 
small.  Pre-heating  and  after-heating,  or  annealing,  are  required 
in  many  instances  to  avoid  locked  up  strains  and  brittleness,  for 
instance  when  welding  cast-iron  or  medium  carbon  steel  or 
higher,  especially  when  the  mass  is  so  great  as  to  cause  rapid 
cooling.  This  subject  will  be  discussed  more  in  detail  in  another 
section  of  this  book. 

The  methods  to  be  followed  vary  in  each  case.  But  the  practice 
ordinarily  used  will  be  shown  in  greater  detail  in  the  articles 
devoted  to  the  practice  employed  for  various  welds  and  different 
conditions.  It  is  necessary,  however,  to  emphasize  the  fact  that 
the  effects  of  the  heat  on  the  structural  arrangement  of  the  metal 
and  the  phenomena  of  expansion  and  contraction  are  enemies  to 
the  welder,  and  in  most  cases  means  must  be  provided  to*  prevent 
their  effects  and  avoid  their  consequences. 

Proper  Access  for  the  Execution  of  the  Welding  Process. — 
To  provide  proper  access  for  making  a  weld,  the  operator  must 
be  free  to  manipulate  the  arc  and  be  able  to  incline  the  electrode 
to  the  proper  angle  with  the  surfaces  on  which  metal  is  to  be 
added.  Also  the  beveling,  spacing  and  arrangement  of  the  work 
must  be  such  as  to  permit  this  manipulation  and  the  use  of  various 
electrode  angles  necessary  to  secure  proper  fusion  through  the 
entire  thickness  of  a  weld. 

Preparation  of  Joints. — There  are  various  types  of  joints 


PREPARATION  OF  WORK 


129 


I 


130  ELECTRIC  ARC   WELDING 

more  or  less  in  use  depending  upon  the  nature  of  the  work  and 
conditions.  The  ones  used  in  a  great  majority  of  cases,  however, 
are  the  double  bevel  and  double  "V,"  Fig.  58.  The  preparation  of 
the  edges,  free  space  or  opening  between  edges,  dimensions  of 
reinforcement,  etc.,  have  an  importance  which  deserves  careful 
consideration  if  efficient  results  are  to  be  had. 

The  usual  practice  has  been  to  provide  an  opening  sufficiently 
large  (usually  not  less  than  a  total  of  90  deg.)  to  give  a  large 
margin  of  assurance  of  ample  access  for  the  deposition  of  the 
metal.  Experience  has  shown  that  better  results,  with  consider- 
able saving  in  time,  welding  material  and  heat  energy,  can  be 
secured  with  smaller  openings.  The  evident  purpose  of  beveling 


— >|    (< — Space  slightly  over  diam. 
of  Electrode  used 

FIG.  59 — Showing  Free  Space  Neces-    FIG.  60 — Method  Used  Where  no 
sary  for  Best  Welding  Results  Free  Space  Can  Be  Allowed  at 

Bottom 

the  edges  is  to  permit  fusion  through  the  entire  section  of  the 
joint  Any  metal  removed,  not  necessitated  by  this,  is  a  waste  of 
time  and  material  and,  moreover,  such  metal  must  usually  be  re- 
placed with  a  metal  inferior  to  that  removed,  especially  if  the 
part  has  had  mechanical  treatment. 

A_few  simple  rules,  which  will  be  useful  in  determining  the 
free  space  (separation  between  edges),  angle  of  bevel,  or  total 
opening  for  double  bevel  and  double  "V"  butt  joints,  and  dimen- 
sions of  reinforcement,  are  given  below: 

Free  Space :     This  is  shown  by  Fig.  59. 

Total  Opening:  It  is  not  necessary  that  the  electrode  be  held 
at  right  angles  to  the  surface  on  which  metal  is  to  be  deposited. 
The  electrode  may  be  inclined  from  this  position  approximately 
30  deg.  without  bad  effects.  For  this  reason  a  total  opening  of  90 
deg.  is  not  required  in  most  cases.  A  total  opening  of  60  deg., 


PREPARATION  OF  WORK 


131 


Fig.  59,  will  permit  ample  access  to  the  surfaces  to  be  joined  and 
will  effect  a  saving  in  time  and  material  of  at  least  10  per  cent 
over  the  90  deg.  opening. 

In  cases  where  no  free  space  can  be  allowed  the  bottom  of  the 
"V"  may  be  cut  to  a  90  deg.  angle  for  a  short  distance,  then  reduc- 
ing the  angle  to  60  deg.  for  the  remainder  of  the  scarf,  as  shown 
by  Fig.  60. 

In  certain  cases  of  unavoidable,  excessive  free  space,  or  on 
light  work  of  low  thermal  capacity,  a  straight  edge  may  be  left 
at  the  bottom  of  the  "V,"  as  shown  by  Fig.  61,  with  a  consider- 
able saving  in  time.  As  a  thin  edge  would  likely  be  melted  down 
in  such  a  case,  leaving  a  large  opening  to  be  filled  in,  there  is 
basis  for  the  belief  that  this  method  of  beveling  may  come  into 
extensive  use  in  the  future. 


-60°- 

\      7 


„  n  . 

&  Approximately 


FIG.  61 


Dimension  L  shoula    T  ^Diameter  R5hould  be 
be  \\  W.  I '^T  for  parts  subject 

to  high  tension. 

FIG.  62 — Reinforced  Weld   Section 


The  strength  of  the  weld  is  not  usually  equal  to  that  of  the 
original  part.  To  compensate  for  this  and  to  secure  a  small 
factor  of  safety,  the  weld  section  should  be  reinforced  when 
conditions  permit,  as  shown  by  Fig.  62.  In  order  that  the  center 
line  of  the  weld  section  will  coincide  with  the  center  line  of  the 
stress,  the  reinforcement  should  be  equal  on  each  side.  The  value 
of  excessive  reinforcements  applied  to  one  side  of  a  joint  is  im- 
paired when  the  part  is  in  tension,  because  of  the  bending  strain 
imposed  on  the  joint.  A  joint  of  this  kind  is  equivalent  to  a 
corrugation  in  a  plate  and  when  placed  in  tension  is  subject  to  the 
same  forces. 

Various  Designs  of  Welds  and  Types  of  Joints  Depending 
on  Service  Requirements. — The  names  used  under  the  sub- 
jects, Type  of  Joint,  Design  of  Welds,  Position  of  Weld,  Kind  of 
Weld,  and  Type  of  Weld,  are  recognized  as  being  proper,  and 


132 


ELECTRIC  ARC   WELDING 


have  been  made  standard  by  the  United  States  Navy.  It  is  to  be 
hoped  that  this  nomenclature  will  be  used  generally  in  order  that 
those  interested  will  use  the  same  welding  terms.  This  is  espe- 
cially necessary  when  preparing  plans  and  specifications  for  use 
in  field  or  shop.  Figs.  58  and  63  show  the  various  designs  of 


STRAP     SYMBOL 


FIG.  63 — Types  of  Joints 

welds  and  types  of  joints  mentioned  in  the  following  discussion: 
Single  "V"  is  a  term  applied  to  the  "edge  finish"  of  a  plate 
when  the  edge  is  beveled  from  both  sides  to  an  angle ;  this  is  used 
when  the  "V"  side  of  the  plate  is  to  be  a  maximum  "strength" 
weld,  with  the  plate  setting  vertically  to  the  face  of  an  adjoining 
member,  and  only  when  the  electrode  can  be  applied  from  both 
sides  of  the  work. 


PREPARATION  OF  WORK  133 

Note :  A  45-deg.  bevel  is  the  most  common  angle  for  a  Single 
"V"  edge  finish.  The  following  table  is  recommended  for  spacing 
indicated  in  Fig.  63  for  Single  "V"  Double  "V"  and  Double 
Bevel: 

Thidkness  Plate  Space 

Above  3%  in.  to  Vs  in 3z  in. 

Above  %  in.  to  %  in %  in. 

Above  Vz  in.  to  %  in &  in. 

Above  %  in %  in. 

Double  <CV"  is  a  term  applied  to  the  "edge  finish"  of  two  ad- 
joining plates  when  the  adjoining  edges  of  both  plates  are  beveled 
from  both  sides  to  an  angle.  To  be  used  when  the  two  plates  are 
to  be  "butted"  together  along  these  two  sides  for  a  maximum 
"strength"  weld ;  only  to  be  used  when  welding  can  be  performed 
from  both  sides  of  the  plate. 

Note :  A  30-deg.  bevel  is  the  most  common  angle  for  a  Double 
"V"  edge  finish. 

Straight  is  a  term  applied  to  the  "edge  finish"  of  a  plate  when 
this  edge  is  left  in  its  crude  or  sheared  state.  Should  only  be  used 
for  thick  plates  where  maximum  strength  is  not  essential,  unless 
used  in  connection  with  strap,  stiffener  or  frame,  or  where  it  is 
impossible  to  otherwise  finish  the  edge.  Also  to  be  used  for  a 
"strength"  weld  with  plate  of  not  more  than  3/16  in.  thickness  or 
when  the  edges  of  two  plates  set  vertically  to  each  other,  as  the 
edge  of  a  box. 

Single  Bevel  is  a  term  applied  to  the  "edge  finish"  of  a  plate, 
when  the  edge  is  beveled  from  one  side  only  to  an  angle.  To  be 
used  for  "strength"  welding  when  the  electrode  can  be  applied 
from  one  side  of  the  plate  only,  or  where  it  is  impossible  to  finish 
the  adjoining  welding  surface. 

Double  Bevel  is  a  term  applied  to  the  "edge  finish"  of  two  ad- 
joining plates,  when  the  adjoining  edges  of  both  plates  are  beveled 
from  one  side  only  to  an  angle.  To  be  used  where  maximum 
strength  is  required,  and  where  the  electrode  can  be  applied  from 
one  side  of  the  work  only. 

Strap  weld  is  one  in  which  the  seam  of  two  adjoining  plates  or 
surfaces  is  reinforced  by  any  form  or  shape  to  add  strength  and 
stability  to  the  joint  or  plate.  In  this  form  of  weld  the  seam  can 


134 


ELECTRIC  ARC   WELDING 


only  be  welded  from  the  side  of  the  work  opposite  the  reinforce- 
ment, and  the  reinforcement  of  whatever  shape  must  be  welded 
from  the  side  of  the  work  to  which  the  reinforcement  is  applied. 

Butt  weld  is  one  in  which  two  plates  or  surfaces  are  brought 
together  edge  to  edge  and  welded  along  the  seam  thus  formed. 
The  two  plates  when  so  welded  form  a  perfectly  flat  plane  in 
themselves,  excluding  the  possible  projection  caused  by  other 
individual  objects  as  frames,  straps,  stiffeners,  etc.,  or  the  build- 
ing up  of  the  weld  proper. 

Lap  weld  is  one  in  which  the  edges  of  two  planes  are  set  one 
above  the  other,  and  the  welding  material  is  so  applied  as  to  bind 


\ 


Flat 


/ 

/ 

rti 

cc 

\ 
\ 

7/ 

/ 

^ 

\ 

ft 

' 

Horizontal 


Overhead 
FIG.  64— Position  of  Welds 

the  edge  of  one  plate  to  the  face  of  the  other  plate.  In  this  form 
of  weld  the  seam  or  lap  forms  a  raised  surface  along  its  entire 
extent. 

Fillet  weld  is  one  in  which  some  fixture  or  member  is  welded  to 
the  face  of  a  plate  by  welding  along  the  vertical  edge  of  the  fixture 
or  member  or  when  metal  is  added  in  a  corner  as  indicated — see 
"welds"  shown  and  marked  A,  (Fig.  63.)  The  welding  ma- 
terial is  applied  in  the  corner  thus  formed  and  is  finished  at  an 
angle  of  45  deg.  to  the  plate. 

Plug  weld  is  used  to  connect  the  metals  by  welding  through  a 
hole  in  one  plate  as  at  A,  or  both  plates  as  at  B ;  also  used  for 
filling  through  a  bolt  hole  as  at  C,  or  for  added  strength  when 
fastening  fixtures  to  the  face  of  a  plate  by  drilling  a  countersunk 


PREPARATION  OF  WORK 


135 


hole  through  the  fixture  as  at  D  and  applying-  the  welding  material 
through  the  hole,  thereby  fastening  the  fixture  to  the  plate. 

Tee  weld  is  one  where  one  plate  is  welded  vertically  to  another 
as  at  A;  also  used  for  welding  a  rod  in  a  vertical  position  to  a  flat 
surface,  as  the  rung  of  a  ladder,  as  at  C,  or  a  plate  welded  ver- 
tically to  a  pipe  stanchion  as  at  B. 

Position  of  Weld. — The  position  of  a  weld  is  shown  in  Fig. 
64,  and  is  determined  as  follows : 

Flat  when  the  welding  material  is  applied  to  a  surface  such 
that  the  electrode  is  held  approximately  vertical  and  the  metal 
flows  in  a  downward  direction.  Horizontal  when  the  welding 


TACK 


SYM00L  7 


SYMBOL  6  CAULKING 


SYMBOL  9 


FIG.  65— Kind  of  Welds 

material  is  applied  to  a  seam,  the  plane  of  which  is  vertical  to  the 
floor  and  the  line  of  weld  is  parallel  with  the  floor.  Vertical 
when  the  line  of  weld  is  perpendicular  to  a  horizontal  plane. 
Overhead  when  the  welding  material  is  applied  to  a  surface  such 
that  the  electrode  is  held  approximately  vertical  and  the  metal 
flows  in  an  upward  direction. 

Kind  of  Weld. — A  Tack  weld  is  one  in  which  the  welding 
material  is  applied  in  small  sections  to  hold  two  edges  together, 
and  should  always  be  specified  by  giving  the  space  from  the  center 
of  one  weld  to  the  center  of  the  next  and  the  length  of  the  weld 
itself.  Can  be  used  with  any  design  of  weld.  A  Tack  weld  is 
also  used  for  temporarily  holding  material  in  place  that  is  to  be 
welded  solid  until  the  proper  alignment  and  position  is  obtained; 


136  ELECTRIC  ARC   WELDING 

in  this  case  neither  the  length,  space  or  design  of  weld  are  to  be 
specified.  Illustrated  in  Fig.  65. 

A  Caulking  weld  is  one  in  which  the  density  of  the  crystalline 
metal,  used  to  close  up  the  seam  or  opening,  is  such  that  no  pos- 
sible leakage  is  visible  under  a  water,  oil  or  air  pressure  of  25  Ib. 
per  sq.  in.  The  ultimate  strength  of  a  caulking  weld  is  not  of 
material  importance.  The  operator  must  be  the  judge  as  to  the 
number  of  layers  needed  for  a  tight  weld,  although  the  designer 
should  specify  a  minimum  number  of  layers.  Illustrated  in 
Fig.  65. 

A  Strength  weld  is  one  in  which  the  sectional  area  of  the  weld- 
ing material  must  be  so  considered  that  its  tensile  strength  and 
elongation  per  square  inch  must  be  equal  to  at  least  80  per  cent 
of  the  ultimate  strength  per  square  inch  of  the  surrounding  ma- 
terial. (To  be  determined  and  specified  by  the  designer.)  The 
welding  material  can  be  applied  in  any  number  of  layers  beyond 
a  minimum  specified  by  the  designer.  The  density  of  the  crystal- 
line metals  is  not  of  vital  importance.  The  design  of  weld  must 
be  specified  by  the  designer  and  followed  by  the  operator.  Illus- 
trated in  Fig.  65. 

A  Composite  weld  is  one  in  which  both  the  strength  and  density 
are  of  vital  importance.  The  strength  must  be  at  least  as  speci- 
fied for  a  "strength  weld,"  and  the  density  must  meet  the  require- 
ments of  a  "caulking  weld,"  both  as  above  defined.  The  mini- 
mum number  of  layers  of  welding  material  must  always  be  speci- 
fied by  the  designer,  but  the  operator  must  be  in  a  position  to 
know  if  this  number  should  be  increased  according  to  the  welders' 
working  conditions.  Illustrated  in  Fig.  65. 

Type  of  Weld. — Reinforced  is  a  term  applied  to  a  weld  when 
the  top  layer  of  the  welding  material  is  built  up  above  the  plane 
of  the  surrounding  material  as  at  A  or  B  (Fig.  66),  or  when  used 
for  a  corner  as  at  C.  The  top  of  the  final  layer  should  project 
above  a  plane  which  is  45  deg.  to  the  adjoining  material ;  this  plane 
is  shown  by  the  dotted  line  in  C.  This  type  of  weld  is  chiefly  used 
in  a  strength  or  composite  kind  of  weld  for  the  purpose  of  ob- 
taining the  maximum  strength,  and  should  be  specified  by  the 
designer,  together  with  a  minimum  number  of  layers  of  welding 
material. 


PREPARATION  OF  WORK 


138  ELECTRIC  ARC   WELDING 

Flush  is  a  term  applied  to  a  weld  when  the  top  layer  is  finished 
perfectly  flat  or  on  the  same  plane  as  the  adjoining  material,  as 
at  D  and  E,  or  at  an  angle  of  45  deg.  when  used  to  connect  two 
surfaces  at  an  angle  to  each  other  as  at  F.  This  type  of  weld  is 
to  be  used  where  a  maximum  tensile  strength  is  not  important 
and  must  be  specified  by  the  designer,  together  with  a  minimum 
number  of  layers  of  welding  material.  Illustrated  in  Fig.  66. 

Concave  is  a  term  applied  to  a  weld  when  the  top  layer  finishes 
below  the  plane  of  the  surrounding  material  as  at  G,  or  beneath  a 
45  deg.  plane  at  an  angular  connection  as  at  H  and  /;  this  type  of 
weld  to  be  for  work  of  no  further  importance  than  filling  in  a 
seam  or  opening,  or  for  strictly  calking  purposes,  when  it  is  found 
that  a  minimum  amount  of  welding  material  will  suffice  to  sustain 
a  specified  pound  per  square  inch  pressure  without  leakage.  It 
will  not  be  necessary  ordinarily  for  the  designer  to  specify  the 
number  of  layers  of  material,  owing  to  the  lack  of  structural 
importance.  Illustrated  in  Fig.  66. 

Conditions  will  determine  the  design  and  type  of  joint  that  can 
be  used,  and  the  service  requirements  will  determine  the  kind  and 
type  of  weld.  For  example :  If  a  square  sheet  is  to  be  welded  in  a 
locomotive  firebox,  the  vertical  seams  should  be  designed  for  a 
double  bevel  and  the  horizontal  seams  for  a  single  bevel,  with  the 
unbeveled  edge  below  the  beveled  edges  in  both  cases.  A  good 
rule  to  follow  in  this  connection  is  never  to  remove  more  of  the 
original  material  than  is  necessary  to  secure  fusion  through  the 
entire  thickness  of  the  parts  to  be  joined.  The  welding  positions 
in  this  case  would  be  horizontal  and  vertical.  The  butt  type  of 
joint  would  be  used.  The  kind  of  weld  would  be  a  strength,  and 
the  type  of  weld,  reinforced. 

In  preparing  plans  embodying  welds,  symbols  may  be  used, 
some  of  which  are  shown  in  Figs.  58,  63,  65  and  66,  to  designate 
Type  of  Joint,  Design  of  Weld,  Position  of  Weld,  Kind  of  Weld, 
and  Type  of  Weld. 

Welding  of  Metal— Thin  to  Thin  and  Thin  to  Heavy.— 
Thin  pieces,  3/32  in.  and  less,  require  no  beveling,  and  in  most 
cases  no  metal  is  added.  The  edges  may  be  butted  together,  or 
preferably  upturned.  They  can  then  be  fused  together,  using  a 
low  current  with  a  ^  in.  electrode  of  carbon  or  graphite  approxi- 


PREPARATION  OF  WORK  139 

mately  6  in.  long  tapered  to  %  in.  at  the  end.  A  certain  amount 
of  skill  is  required  in  welding  thin  pieces,  but  a  little  practice  will 
soon  enable  an  operator  to  do  good  work.  Wire  netting,  etc.,  is 
welded  together  in  the  same  manner  as  thin  plates.  Carbon 
blocks,  pieces  of  cast  iron  or  copper  are  used  sometimes  for  a 
backing  to  conduct  the  heat  away  and  prevent  the  melting  of  the 
edges. 

In  welding  thin  pieces  to  heavy  pieces,  the  conditions  will 
govern  the  preparation  of  the  work.  In  some  cases  this  class  of 
welding  is  more  difficult  to  do  than  is  the  welding  of  parts  of  equal 
thickness.  In  general,  however,  the  electric  process  is  better 
adapted  to  such  work  than  any  other  form  of  autogenous  welding. 

An  example  of  this  class  of  work  is  to  be  found  in  the  welding 
of  boiler  tubes  to  the  tube  sheet.  The  metallic  arc  is  about  the 
only  process  commercially  used.  The  thickness  of  the  tubes  is 
usually  y%  in.  and  the  tube  sheet  ^  in.  The  heat  used  must  be 
sufficient  to  bring  the  thicker  part  up  to  fusion ;  this  will  tend  to 
penetrate  through  the  thinner  part  where  the  difference  in  thick- 
ness is  very  great.  The  work  is  accomplished  by  playing  the 
greater  portion  of  the  arc's  flame  on  the  heavier  piece. 

Preparation  of  Cylinders  and  Vessels  for  Welding. — In  gen- 
eral, the  preparation  of  cylinders  and  vessels  upon  which  welding 
is  to  be  done  will  be  governed  by  the  service  which  determines  the 
stresses  that  may  be  expected  to  be  imposed  upon  the  line  of  the 
weld.  For  vessels  that  are  not  to  be  subjected  to  high  pressures 
or  rough  handling,  the  least  expensive  method  is  the  most  desir- 
able, two  examples  of  which  are  shown  in  Figs.  67  and  68. 

For  vessels  which  are  to  contain  gases  or  liquids  under  high 
pressure,  the  weld  should 'be  in  tension  or  compression,  and  not 
prying  or  binding.  A  butt-weld  head  of  good  design  with  the 
weld  in  tension  is  shown  in  Fig.  69.  A  concave  head  with  the 
weld  in  compression  is  shown  in  Fig.  70,  which  is  by  far  the 
better  and  stronger  construction.  Vessels  having  heads  welded 
in  as  shown  in  Fig.  70  have  been  subjected  to  a  pressure  of  3,600 
Ib.  per  sq.  in.  before  rupture  occurred. 

Longitudinal  Seams  and  the  Preparation  of  Pipes  and 
Tubes  for  Welding. — In  welding  longitudinal  seams  on  round 
tanks,  it  is  first  necessary  to  have  a  perfectly  round  shell ;  that  is, 


140 


ELECTRIC  ARC   WELDING 


the  joining  ends  of  the  sheet  should  not  have  a  flattened  section, 
as  is  customary  when  coming  from  the  bending  rolls.  A  flat 
surface  along  the  line  of  weld  has  a  tendency  to  round  out  under 


FIG.  67  FIG.  68  FIG.  69  FIG.  70 

FIGS.  67  to  70 — Preparing  Cylinders  and  Vessels  for  Welding 

pressure,  and  in  so  doing  places  a  bending  strain  on  the  weld, 
which  is  often  the  cause  of  rupture.  The  "edge  finish"  should  be 
beveled  and  a  butt  type  of  joint  used.  The  contraction  can  be 
allowed  for  by  a  greater  separation  at  one  end  than  at  the  other 


FIG.  72 


FIG.  73 


FIG.  74 


FIG.  71 


HZ 


\ 

s 

s 

\ 

\ 

\ 

t 

i\ 
\ 



i 

Y/S/t 

/"/////y^ 

////////////////I 

75 


.  76 


FIGS.  71  to  76— Preparation  of  Longitudinal  Seams,  Pipes  and  Tubes  for 

Welding 

as  shown  in  Fig.  71.     The  amount  of  opening  should  be  deter- 
mined as  previously  explained. 

In  joining  pipes  together  so  as  to  form  a  straight  piece  the  ends 
should  be  beveled  as  shown  in  Fig.  72.  Pipes  that  are  to  be  joined 
to  form  angles  should  have  the  ends  prepared  as  shown  in  Figs. 


PREPARATION  OF  WORK  141 

73  and  74.  Branches  should  be  prepared  as  shown  in  Figs.  75 
and  76.  Many  pipe  fittings  of  various  kinds  are  constructed  by 
the  arc  process,  and  their  preparation  is  governed  largely  by 
service  requirements  and  the  conditions  under  which  the  operator 
must  work. 


IX 

IRON  AND  STEEL  AND  THE  WELDING  OF  EACH ; 
WELDING  OF  NON-FERROUS  METALS 

Iron  ore  is  combined  usually  with  oxygen,  carbon,  silicon, 
sulphur  and  phosphorus,  the  combinations  being  known  as  iron 
oxide — brown  or  red  in  color — iron  carbonate,  iron  silicate,  iron 
sulphate,  iron  phosphate,  etc.  The  mining  of  this  ore  and  its  con- 
version into  iron  and  steel  products  forms  one  of  the  world's 
greatest  industries.  The  ore  is  smelted  in  blast  furnaces  to  pro- 
duce metallic  iron.  The  process  consists  essentially  of  the  re- 
moval of  the  oxygen,  which  is  combined  with  the  iron.  The 
product,  however,  is  not  chemically  pure  iron.  Pure  iron  is  a 
laboratory  product  and  on  account  of  the  high  cost  of  production, 
it  is  not  used  commercially.  The  metal  which  comes  from  blast 
furnaces  is  known  as  pig  iron  and  contains  the  following  ele- 
ments :  iron,  carbon,  silicon,  manganese,  sulphur,  phosphorus, 
and  minute  quantities  of  gases,  oxygen,  nitrogen,  etc.  Solid  solu- 
tions and  chemical  compounds  of  these  elements  exist  in  the 
metal  but  for  the  purpose  here  desired  it  is  sufficient  to  state  that 
these  elements  are  present  in  the  metal  in  some  form. 

Various  Kinds  of  Iron  and  Steel. — Cast  iron,  steel,  and 
wrought  iron  constitute  the  group  of  products  which  we  classify 
under  the  names  iron  and  steel.  These  products  have  two  points 
in  common :  First,  iron  is  present  in  all  cast  iron  to  the  extent  of 
at  least  92  per  cent,  and  in  steel  and  wrought  iron  the  per  cent 
varies  usually  from  97  to  100;  second,  the  per  cent  of  carbon 
present  and  the  form  or  physical  condition  in  which  this  carbon 
exists  in  the  metal  is  the  chief  factor  governing  the  physical 
characteristics  of  the  finished  product. 

Pig  iron  is  impure,  weak,  and  is  brought  to  its  desired  form  by 
melting  and  casting  in  a  mold.  Cast  iron  is  pig  iron  cast  into  some 

desired  commercial  shape. 

142 


IRON,  STEEL  AND  NON-FERROUS  METALS          143 

Steel  is  purer  than  cast  iron.  It  is  much  stronger,  and  may  be 
produced  in  the  desired  foim,  either  by  melting  and  casting  in  a 
mold  or  by  forging  at  a  red  heat.  Forgings  usually  contain  about 
98  per  cent,  or  more,  of  iron  and  from  1.5  per  cent  down  to  almost 
no  carbon,  together  with  small  amounts  of  other  ingredients  or 
impurities. 

Wrought  iron  is  almost  the  same  as  the  very  low  carbon  steel, 
except  that  it  is  never  produced  by  melting  in  a  mold,  but  is  forged 
to  the  desired  size  and  form.  In  general  it  contains  less  than  0.12 
per  cent  carbon.  Its  chief  distinction  from  low  carbon  steel  is 
that  it  is  made  by  a  process  which  works  it  in  a  pasty  instead  of  a 
liquid  form,  and  leaves  about  1  or  2  per  cent  of  slag  mechanically 
disseminated  through  it. 

Cast  Iron ;  Gray,  White  and  Malleable. — Cast  iron  has  three 
forms ;  namely,  gray  cast  iron,  white  cast  iron,  and  malleable  cast 
iron.  The  following  is  a  typical  analysis  of  cast  iron : 

Element  Percentage 
Carbon — 

Combined  carbon  0.50  to      0.75 

Free  carbon,  or  graphite 2.75  to       3.00 

Silicon    1.00  to      3.00 

Manganese    0.50  to      1.00 

Phosphorus   0.50  to      1.00 

Sulphur    0.085  to      0.15 

Iron    .  94.665  to  91.10 


Total    100.000       100.00 

Gray  cast  iron  and  white  cast  iron  may  have  about  the  same 
total  amount  of  impurities.  The  amount  of  free  carbon  in  the 
form  of  graphite  in  gray  iron  is  very  large.  This  gives  the  gray 
appearance  which  a  fracture  shows  and  from  which  the  name  is 
derived.  Graphite  having  no  strength  of  its  own  and  being  pres- 
ent in  the  metal,  breaks  up  the  metallic  structure  of  the  body, 
thus  leaving  lines  of  weakness.  Gray  cast  iron  usually  contains  2 
per  cent  or  more  of  graphite,  and  less  than  \y2  per  cent  of  com- 
bined carbon.  The  graphite  is  not  in  chemical  combination  with 
the  metal,  but  is  mechanically  mixed  with  it. 

Silicon,  sulphur,  phosphorus,  and  manganese,  all  have  an  in- 
fluence upon  cast  iron.  Three  per  cent  or  less  of  silicon  tends  to 
decrease  the  amount  of  combined  carbon  and  consequently  de- 


144  ELECTRIC  ARC   WELDING 

creases  the  hardness  of  the  product.  Sulphur  and  phosphorus 
are  the  impurities  which  tend  to  weaken  iron  most,  disregarding 
their  influence  on  carbon.  'Manganese  has  a  varying  effect.  For 
the  purpose  here  desired  it  is  sufficient  to  state  that  manganese 
assists  in  counteracting  the  bad  effects  of  sulphur;  also  it  varies 
the  degree  of  hardness. 

Some  of  the  disadvantages  of  cast  iron  are  its  weakness  and 
lack  of  ductility  and  malleability.  The  last  named'  deficiency 
renders  it  undesirable  for  many  commercial  and  engineering  pur- 
poses. It  is  used  for  castings  that  are  to  be  subjected  only  to 
compression  or  moderate  transverse  or  tensile  strains;  as  for 
example,  supporting  columns,  engine  bed-plates,  water  mains,  etc. 

The  chief  advantages  of  cast  iron  are  cheapness  and  the  fusi- 
bility which  makes  it  easy  to  melt  and  cast  the  product.  The 
tensile  strength  of  cast  iron  is  about  one-half  that  of  steel,  being 
approximately  28,000  Ib.  per  sq.  in.  for  soft  iron.  Cast  iron  has 
no  elasticity  and  there  is  no  elongation  before  rupture. 

Welding  of  Cast  Iron. — It  is  difficult  to  weld  cast  iron  by 
any  process  under  the  most  favorable  conditions,  due  to  the  high 
percentage  of  impurities,  low  tensile  strength,  and  above  all  the 
effect  of  a  localized  heat.  Its  brittleness,  lack  of  elasticity  and 
weakness  also  complicate  matters.  In  the  case  of  metallic  arc 
welding,  expansion  and  contraction  are  minimized  to  a  greater 
extent  than  with  any  other  welding  process,  owing  to  the  extreme 
localization  of  the  arc  flame. 

When  the  electric  arc  is  used  for  cast  iron  welding,  about  the 
only  precaution  exercised  is  to  hold  the  heat  in  the  casting  to  a 
low  value  by  using  a  small  size  electrode  with  a  correspondingly 
low  heat  value,  and  even  in  some  cases  prolonging  the  work.  The 
metal  should  be  applied  in  sections  as  has  been  described  in  a 
previous  part  of  this  book. 

The  welding  of  cast  iron  by  the  carbon  arc  requires  essentially 
the  same  precautions  regarding  expansion  and  contraction  as  is 
required  with  the  oxy-acetylene  process,  in  which  case  pre-heating 
is  usually  employed  unless  the  parts  are  small  and  free  to  move,  in 
which  case  pre-heating  may  not  be  necessary. 

The  effect  of  the  heat  from  the  arc  on  the  part  to  which  it  is 
applied  is  the  most  difficult  obstacle  to  overcome  in  welding  cast 


IRON,  STEEL  AND  NON-FERROUS  METALS 


145 


iron.  The  condition  produced  by  the  application  of  an  arc  on 
cast  iron,  especially  the  metallic  arc,  is  the  equivalent  to  that  em- 
ployed to  produce  white  cast  iron ;  that  is,  when  a  localized  heat 
is  applied  to  a  piece  of  cast  iron  a  small  area  is  brought  up  to  a 
state  of  fusion  and  as  the  localized  heat  is  moved  to  another  loca- 
tion the  first  point  heated  will  chill,  or  cool  suddenly  and  prevent 
the  precipitation  of  the  carbon  in  the  form  of  graphite ;  in  other 
words  the  carbon  will  be  left  combined  in  the  iron,  leaving  it  very 
hard  and  difficult  to  work. 

For  example,  assume  that  metal  has  been  added  to  a  gray  iron 


AfeM  Cast  5 fee/ 
Cast  Iron 
Graf/  Cast  Jrorr. 


FIG.  77— In  the  Completed  Weld  There  Are  Three  Kinds  of  Metal 

casting  by  the  metallic  arc  process,  which  requires  the  use  of  an 
iron  or  steel  electrode.  In  the  completed  weld  there  are  three 
kinds  of  metal  as  shown  in  Fig.  77.  The  original  gray  cast  iron 
immediately  under  the  added  metal  or  under  the  line  of  union  has 
been  changed  to  white  cast  iron  on  account  of  the  chilling  effect ; 
above  the  white  cast  iron  is  the  added  metal,  cast  steel,  the  first 
layer  of  which  is  very  hard,  on  account  of  the  carbon  in  the  cast 
iron  combining  with  the  steel  when  the  two  were  in  a  molten 
state;  in  fact  a  portion  of  this  first  layer  might  be  called  semi- 
steel  and  on  cooling  small  checks  usually  develop.  The  second 
layer  is  much  softer,  and  can  be  machined  without  difficulty. 

Machining  the  Parts  Welded. — If  the  casting  is  to  be  ma- 
chined in  the  welded  section,  it  must  first  be  annealed.    In  prac- 


146 


ELECTRIC  ARC   WELDING 


tice  this  is  seldom  done,  because  there  are  methods  which  make  it 
unnecessary  to  machine  through  the  welded  section,  thus  avoiding 
pre-heating  or  annealing.  For  example,  broken  cast  iron  locomo- 
tive cylinders  are  often  repaired  by  first  boring  them  out  and 
applying  a  bushing.  The  fracture  is  then  V'd  out  in  the  usual 
manner  and  iron  studs  are  placed  along  the  line  of  weld.  Fig.  78 
shows  a  weld  prepared  in  this  manner  partially  finished. 

The  studs  serve  a  double  purpose ;  that  is,  the  welding  is  started 


FIG.    78— Broken    Cast    Iron    Locomotive    Cylinder,    Left    Side    Showing 
Fracture  Partially  Welded  with  Arc  Welder 

around  the  studs,  which  makes  the  depositing  of  the  metal  easier, 
and  also  since  the  studs  extend  through  the  line  of  union  as  well 
as  through  the  heat  affected  zone,  a  factor  of  safety  is  assured. 
Without  the  studs  the  heat  affected  zone  usually  develops  checks, 
and  finally  complete  rupture  when  subjected  to  alternate  stresses. 
Another  method  by  which  machining  through  the  heat  affected 
zone  may  be  avoided  in  the  case  of  welding  cylinders  or  similar 
parts,  is  shown  in  Fig.  79.  The  soft  iron  or  copper  rod  insert  can 
be  worked  into  place  with  a  peening  hammer  and  afterwards  be 
machined,  or  filed  and  scraped,  to  conform  to  the  contour  of  the 
cylinder.  In  either  case  it  is  possible  to  bore  the  cylinder  if  neces- 


IRON,  STEEL  AND  NON-FERROUS  METALS          147 

sary.  The  methods  indicated  above  are  used  extensively  and  are 
known  to  be  successful  in  connection  with  metallic  arc  welding. 

There  are  many  cases  where  a  surface  can  be  finished  with  a 
grinder ;  as  for  example,  to  secure  a  smooth  surface  for  a  steam 
tight  joint.  There  are  also  many  cases  that  do  not  require  finish- 
ing of  any  kind  along  the  line  of  weld. 

The  welding  of  cast  iron  by  the  carbon  arc,  in  most  cases, 
requires  a  method  very  similar  to  that  used  in  connection  with  the 
oxy-acetylene  process,  since  the  area  heated  by  the  carbon  arc 
process  is  not  so  localized  as  that  of  the  metallic  arc.  It  is  there- 


Secf/on    uneffected  by 
Me  heat  of  the  arc. 


FIG.    79 — Method   of    Welding   Used   to   Avoid   the    Need   of    Machining 
Through  the  Heat  Affected  Zone 

fore  not  only  necessary  to  take  very  special  precautions  to  prevent 
bad  effects  from  expansion  and  contraction,  but  it  is  also  neces- 
sary that  the  line  of  weld  should  consist  of  metal  that  is  workable. 
The  conditions  to  be  observed  in  order  to  produce  a  weld  in 
gray  iron  that  is  workable  are:  (1)  Slow  cooling.  (2)  Introduc- 
tion of  silicon  in  the  welding  bed.  (3)  Absence  of  manganese. 
It  will  be  remembered  that  rapid  cooling  of  the  metal  in  fusion 
tends  to  bring  about  the  combination  of  the  carbon  and  the  iron ; 
that  is  to  say,  the  formation  of  white  cast  iron,  which  is  unde- 
sirable. On  the  other  hand,  slow  cooling  tends  to  bring  about  the 
precipitation  of  the  carbon  producing  a  soft  iron.  The  silicon 
assists  in  decreasing  the  combined  carbon,  thus  opposing  hardness. 
The  effect  of  manganese  is  opposite  to  that  of  silicon  and  is  there- 
fore undesirable.  The  effects  of  expansion  and  contraction  are 
provided  for  by  pre-heating  every  part  of  the  object,  or  by  any 
other  treatment  to  bring  about  the  same  result. 


148  ELECTRIC  ARC   WELDING 

The  question  of  cast  iron  welding  is  very  important;  on  this 
account  the  authors  solicited  the  following  contribution  from 
Robert  E.  Kinkead,  welding  engineer. 

Reclamation  of  Cast  Iron  Parts 

"The  salvage  of  broken  and  defective  gray  iron  castings  is  one 
of  the  most  important  fields  in  which  welding  plays  a  part. 

"A  gray  iron  casting  may  be  worth  from  three  to  twenty  times 
its  scrap  value  due  to  the  labor  and  machinery  required  to  get  it 
into  a  form  which  has  utility  for  a  particular  purpose.  If  the 
casting  is  broken  or  slightly  imperfect  in  the  foundry  it  has  no 
utility  whatever  for  the  purpose  for  which  it  was  intended.  As- 
suming that  the  casting  is  broken  in  service,  the  parts  have  only  a 
scrap  value.  The  labor  and  other  charges  which  were  incurred 
in  getting  the  metal  into  the  form  required  are  entirely  lost. 
When  it  is  considered  that  thousands  of  tons  of  material  of  this 
nature  are  scrapped  every  year,  the  enormous  economic  waste 
from  this  source  may  be  realized. 

' 'Another  phase  of  this  subject  and  one  in  which  the  economic 
loss  is  inestimable  arises  from  the  loss  due  to  the  failure  of  cast- 
ings which  in  turn  cause  loss  of  production.  There  is  no  doubt 
but  the  economic  loss  from  this  source  approaches  the  economic 
loss  due  to  the  loss  of  labor  and  expense  in  the  manufacture  of 
the  casting  itself. 

"The  earliest  method  of  welding  cast  iron  was  developed  in  the 
foundry.  In  this  case  the  process  is  called  'burning  a  casting.' 
The  casting  is  imbedded  in  foundry  sand  and  sufficient  hot  metal 
run  over  the  fractured  part  to  bring  it  up  to  a  high  enough  tem- 
perature to  make  the  metal  plastic.  At  this  point  the  pouring  of 
metal  is  stopped  and  the  metal  at  the  point  to  be  welded  is  allowed 
to  cool  into  a  homogeneous  mass  with  the  metal  of  the  original 
casting.  This  method  of  'burning'  defective  or  broken  castings 
is  entirely  successful  but  is  somewhat  expensive. 

"The  introduction  of  the  thermit  and  oxy-acetylene  welding 
processes  brought  about  successful  means  of  repairing  practically 
any  defect  or  break  ever  encountered  in  gray  iron  castings.  The 
work  of  these  two  processes  is  nothing  short  of  marvelous.  It  is 


IRON,  STEEL  AND  NON-FERROUS  METALS         149 

only  necessary  to  visit  a  few  of  the  commercial  welding  shops  in 
the  country  to  see  the  wide  variety  of  castings  that  are  welded  and 
put  back  into  service,  for  all  practical  purposes  as  good  as  new. 

"The  use  of  the  thermit  and  oxy-acetylene  welding  process  is 
somewhat  expensive.  What  is  saved  by  their  use  is  in  most  cases 
the  loss  of  production  or  use  of  the  casting  due  to  the  fact  that  a 
replacement  part  is  not  immediately  available.  In  many  cases,  the 
cost  of  applying  either  of  these  processes  is  equal  to  or  greater 
than  the  cost  of  a  new  casting. 

"In  applying  the  electric  arc  welding  process  to  the  welding  of 
cast  iron,  we  are  attempting  to  lower  the  cost  of  the  welding  so 
that  in  addition  to  the  saving  which  can  be  accomplished  using 
the  thermit  and  oxy-acetylene  processes,  we  can  save  a  large  per- 
centage of  the  cost  of  the  labor  involved  in  manufacturing  the 
casting.  The  development  of  the  application  of  the  electric  arc 
welding  process  to  the  welding  of  cast  iron  has  gone  forward 
slowly  for  a  number  of  very  apparent  causes.  The  most  impor- 
tant cause  for  the  delay  in  the  application  of  the  electric  welding 
process  to  cast  iron  is  probably  the  difficulty  of  its  application. 
Another  important  factor  is  that  the  cost  of  electric  arc  welding 
equipment  is  comparatively  high  so  that  the  number  of  operators 
who  have  had  an  opportunity  to  work  on  the  problem  is  somewhat 
limited.  In  spite  of.  the  difficulties  some  progress  has  been  made. 
It  seems  certain  that  the  electric  arc  process  will  be  used  quite 
extensively  in  the  future  in  this  class  of  work  for  the  reason  that 
whenever  it  becomes  possible  to  do  a  job  at  a  lower  cost  than  it 
has  been  done  heretofore  that  new  process  becomes  economically 
necessary. 

Cast  Iron  Welding  by  Metallic  Arc 

"Some  important  work  has  been  done  with  the  metal  electrode 
process  in  the  welding  of  gray  iron  castings  cold.  Among  certain 
welding  interests  the  tendency  is  to  over-estimate  the  importance 
of  this  application  and  to  under-estimate  the  dangers,  which  would 
be  encountered  if  this  practice  should  ever  become  general.  The 
work  done  in  this  manner  is  accomplished  by  merely  fusing  a 
steel  electrode  to  'the  cast  iron.  Steel  studs  are  inserted  in  the 
edges  of  the  cast  iron  pieces  to  be  welded  and  the  welded  material 


150  ELECTRIC  ARC   WELDING 

is  bridged  between  the  studs  as  well  as  being  fused  to  the  cast 
iron  of  the  original  pieces. 

"The  ultimate  strength  which  may  be  expected  from  such  a  joint 
is  the  shearing  strength  of  the  studs,  minus  the  strength  of  the 
original  pieces  sacrificed  by  the  drilling  of  the  holes  for  the  studs, 
plus  whatever  strength  is  obtained  by  the  fused  joint  between  the 
steel  and  the  cast  iron.  This  latter  strength  is  sometimes  esti- 
mated at  a  maximum  of  5,000  Ib.  per  sq.  in.  However,  actual 
experience  shows  that  no  reliance  can  be  placed  on  such  a  joint 
between  steel  and  gray  iron.  The  difficulty  with  such  a  joint  is 
fundamental.  If  a  casting  is  not  pre-heated,  the  cast  iron  ad- 
jacent to  the  line  of  fusion  is  hard  and  brittle  because  of  the  fact 
that  it  was  melted  and  cooled  very  suddenly. 

"On  the  steel  side  of  the  weld,  if  fusion  is  accomplished  be- 
tween steel  and  cast  iron,  owing  to  the  high  solubility  of  carbon 
in  steel  a  certain  amount  of  carbon  from  the  cast  iron  is  absorbed 
by  the  steel  added,  thus  giving  a  high  carbon  steel  adjacent  to  the 
line  of  fusion  on  the  steel  side.  There  are  a  number  of  applica- 
tions where  this  kind  of  welding  is  entirely  satisfactory  and 
results  in  a  large  economic  saving,  but  wherever  the  failure  of  a 
welded  casting  carries  with  it  possibilities  of  death  and  destruc- 
tion, such  a  joint  should  be  used  with  great  caution. 

"A  great  many  attempts  have  been  made  to. get  around  the  fun- 
damental metallurgical  difficulties  encountered  in  this  kind  of 
work  but  so  far  no  one  has  been  able  to  put  anything  in  the  weld- 
ing wire  or  on  the  electrode  or  on  the  cast  iron  that  materially 
changes  the  fundamental  limitations  of  the  process  on  this  ap- 
plication. 

Cast  Iron  Welding  by  Carbon  Arc 

"Welding  gray  iron  castings  with  the  carbon  electrode  electric 
arc  welding  process  using  a  cast  iron  melt  bar  has  been  shown  to 
be  entirely  practicable  over  a  wide  range  of  applications.  The 
only  difference  between  this  method  of  welding  and  that  by  the 
oxy-acetylene  process  is  that  the  source  of  heat  for  welding  is  an 
electric  arc  instead  of  an  oxy-acetylene  flame.  It  is  quite  true  that 
the  difficulty  in  manipulating  an  electric  arc  is  somewhat  greater 
than  the  difficulty  in  manipulating  an  oxy-acetylene  flame.  The 


IRON,  STEEL  AND  NON-FERROUS  METALS          151 

reason  the  arc  is  difficult  to  manipulate  is  that  the  operator  must 
use  the  full  temperature  of  the  arc  or  must  break  it  entirely. 
There  is  no  intermediate  point  between. 

"The  corresponding  case  in  the  oxy-acetylene  welding  is  that  in 
which  the  operator  believes  he  is  getting  the  metal  too  hot  and 
can  merely  back  away  from  the  casting  with  the  torch,  thus 
reducing  the  temperature  but  without  breaking  the  continuity  of 
the  welding  heat.  The  particular  difficulty  encountered  in  the 
manipulation  of  the  arc  owing  to  this  fact  arises  in  the  case  of  thin 
sections  where  the  tendency  is  for  the  arc  to  burn  through ;  also 
in  the  welding  of  vertical  or  practically  vertical  surfaces.  The 
temperature  of  the  arc  is  so  high  that  the  metal  runs  rapidly  and 
it  is  extremely  difficult  to  weld  on  a  vertical  surface.  With  the 
oxy-acetylene  flame  the  temperature  may  be  reduced  so  that  the 
iron  is  in  such  a  plastic  state  a  vertical  weld  may  be  accomplished. 

Future  Development  of  Cast  Iron  Welding  Methods 

"Some  experiments  are  being  carried  on  at  the  present  time 
using  a  cast  iron  electrode  and  using  the  metal  electrode  process 
of  electric  arc  welding.  In  order  to  work  the  metal  this  way,  it  is 
necessary  to  have  some  kind  of  a  covering  for  the  cast  iron  elec- 
trode to  make  the  cast  iron  run  with  a  reasonable  degree  of 
smoothness  through  the  arc.  The  possibilities  of  this  method  of 
welding  cast  iron  with  the  electric  arc  process  seem  to  be  great. 

"In  welding  cast  iron  either  with  the  carbon  arc  and  cast  iron 
melt  bar,  or  with  the  metallic  arc  using  cast  iron  electrode,  it  is 
necessary  to  pre-heat  the  casting  in  exactly  the  same  manner  as  if 
it  were  being  welded  with  the  oxy-acetylene  flame.  Care  in  cool- 
ing must  be  exercised  to  the  same  degree  .as  if  the  gas  flame  were 
used. 

"Work  is  also  being  done  at  the  present  time  in  the  direction 
of  using  two  carbon  electrodes  and  not  using  the  gray  iron  casting 
as  one  electrode.  The  object  here  is  to  get  the  carbon  arc  inde- 
pendent of  the  casting  and  to  make  it  possible  for  the  operator  to 
reduce  the  temperature  and  total  heat  applied  to  the  point  at  which 
the  welding  is  to  be  done  in  much  the  same  manner  as  he  can  do 
when  using  the  gas  flame.  This,  should  it  prove  successful,  would 


152  ELECTRIC  ARC   WELDING 

enable  the  operator  to  work  the  iron  at  a  temperature  at  which  it 
is  plastic  and  would  overcome  the  most  important  difficulties  in 
the  way  of  welding  cast  iron  with  the  electric  arc  process.  So  far 
the  apparatus  produced  for  this  method  of  welding  has  been  cum- 
bersome and  difficult  to  manipulate  but  there  seems  to  be  a  field 
for  improvement  of  the  apparatus  and  there  is  reason  to  believe 
that  the  difficulties  will  be  overcome. 

"Some  very  interesting  and  original  work  was  done  several 
years  ago  by  Mr.  L.  B.  Brewster,  who  was  at  that  time  chief 
chemist  of  the  Ferro  Machine  &  Foundry  Company  at  Cleveland, 
Ohio.  He  developed  a  method  of  repairing  small  defects  in  gray 
iron  castings  using  a  nickel  electrode.  The  advantage  of  this 
process  as  compared  with  the  use  of  a  steel  electrode  is  that  the 
nickel  cannot  be  hardened  by  the  absorption  of  carbon  from  the 
cast  iron.  The  line  of  demarkation  in  such  a  joint  between  the 
nickel  and  the  cast  iron  is  an  example  of  adhesion  rather  than  an 
example  of  cohesion.  There  is  an  inappreciable  degree  O'f  strength 
in  the  joint.  Where  a  small  defect  is  filled  with  nickel  by  this 
process  the  nickel  is  peened  into  the  defect  with  a  hammer  so  that 
the  small  spaces  are  filled  up  with  nickel  and  the  added  material 
is  held  in  place  mechanically  rather  than  by  a  fused  joint.  This 
process  is  in  every  way  similar  mechanically  to  the  process  the 
dentist  uses  in  filling  a  cavity  in  a  tooth  using  a  mercury  silver 
amalgam.  Since  the  coefficient  of  expansion  of  nickel  is  some- 
where near  the  coefficient  of  expansion  of  cast  iron,  no  difficulty 
is  experienced  from  the  added  material  coming  out  over  the  heat 
range  encountered  in  most  castings.  The  nickel  is  somewhat 
softer  than  cast  iron  and  on  a  wearing  surface  no  difficulty  is 
encountered  from  this  source.  However,  the  limitation  of  the 
process  comes  from  the  fact  that  if  the  cast  iron  is  actually  melted 
by  the  arc,  and  it  in  most  cases  is,  a  hard  line  is  left  around  the 
margin  of  the  defect  filled  in  this  manner.  This  hard  line  inter- 
feres with  machining  to  a  certain  extent. 

"In  spite  of  the  difficulties  mentioned,  a  number  of  concerns  are 
using  this  process  in  the  correction  of  small  defects  in  automobile 
cylinder  engines.  In  this  case  by  skillful  manipulation  the  nickel 
is  anchored  in  the  bottom  of  the  defect  and  the  arc  is  not  allowed 
to  strike  anyway  near  the  machined  surface  of  the  cylinder.  The 


IRON,  STEEL  AND  NON-FERROUS  METALS          153 

nickel  is  peened  securely  into  the  defect  and  the  excess  is  filed  or 
scraped  away. 

"Some  work  has  been  done  using  brazing  wire  for  the  metal 
electrode  in  the  electric  arc  process.  A  brazing  job  accomplished 
in  this  manner  is  not  very  reliable  for  the  reason  that  fusing  the 
brazing  rod,  the  zinc  is  vaporized  sooner  than  the  other  elements 
of  the  metal  and  this  causes  violent  bubbling  and  porosity  of  the 
added  brass. 

"The  status  of  the  application  of  electric  arc  welding  to  the 
welding  of  gray  iron  castings  at  the  present  time  may  be  sum- 
marized as  follows : 

"With  reference  to  the  oxy-acetylene  and  thermit  processes 
which  are  recognized  as  successful  processes  at  the  present  time, 
the  carbon  electrode  method  of  welding  with  the  electric  arc  can 
be  used  on  sections  thicker  than  a  quarter  of  an  inch,  where  the 
weld  may  be  made  in  the  horizontal  position,  as  well  as  either  of 
the  other  two  processes  and  at  a  considerably  lower  cost.  In  this 
case  the  electric  arc  is  used  as  a  source  of  welding  heat  and  the 
practice  followed  is  from  a  metallurgical  point  of  view  the  same 
as  in  the  case  of  the  oxy-acetylene  flame.  There  is  no  greater 
danger  of  hardness  of  the  weld  when  properly  treated  in  the  case 
of  the  electric  arc  than  in  the  case  of  the  oxy-acetylene  flame.  On 
certain  specific  applications  the  steel  electrode  and  metal  electrode 
process  is  entirely  practicable  and  much  cheaper  than  any  process 
so  far  used, — but  great  care  must  be  used  in  its  application  to 
avoid  disastrous  failures." 

White  Cast  Iron. — White  cast  iron  is  made  of  metal  of  the 
same  chemical  composition  as  is  used  to  make  gray  iron  castings. 
The  molten  metal  is  cast  in  cold  molds  and  is  thereby  "chilled." 
It  is  evident  that  no  very  great  change  in  the  chemical  composition 
could  take  place  in  this  chilling  process.  However,  the  sudden 
cooling  denies  the  carbon  the  time  to  change  into  the  graphitic 
form.  Chilled  iron  is  hard  and  brittle.  The  white  appearance 
of  the  fracture  of  the  metal  reveals  its  name,  and  is  due  to  the 
comparatively  small  amount  of  free  carbon  present  in  the  metal. 

There  are  cases  where  it  is  desirable  to  have  one  surface  of  a 
casting  very  hard  in  order  to  resist  wear,  such  as  the  tread  of 
car  wheels  and  the  working  face  of  anvils,  etc.  To  do  this  it  is 


154  ELECTRIC  ARC   WELDING 

only  necessary  to  chill  the  surface  so  as  to  produce  white  cast 
iron  to  varying  depths.  There  is  little  occasion  for  welding  white 
cast  iron  and  besides  in  most  cases  it  is  not  commercially  prac- 
ticable owing  to  the  effect  of  the  localized  heat. 

Malleable  Cast  Iron. — Malleable  cast  iron  has  physical 
properties  between  gray  iron  and  steel  castings.  Its  tensile 
strength  varies  between  40,000  and  60,000  Ib.  per  sq.  in.  with  an 
elongation  of  2l/2  to  5^  per  cent  in  2  in.  Malleable  castings  are 
made  by  reheating  white  iron,  packed  in  some  material  such  as 
lime,  etc.,  heated  to  a  temperature  roughly  840  deg.  Fahr.  under 
its  melting  point.  They  are  kept  at  this  temperature  for  hours 
or  days  and  under  these  conditions  the  combined  carbon  as  it 
existed  in  the  form  of  white  iron  is  freed  in  the  form  of  pow- 
dered graphite,  unlike  the  graphite  in  gray  iron  which  is  in  the 
form  of  flakes.  Since  ferrite  or  free  iron  is  soft  and  malleable 
the  annealed  casting  partakes  of  these  properties  and  is  called  a 
malleable  casting.  Annealed  castings  seldom  show  the  effects 
of  the  annealing  throughout  the  entire  mass;  as  a  rule  the  an- 
nealing does  not  produce  a  noticeable  effect  beyond  a  fraction  of 
an  inch  below  the  surface  of  the  casting.  Usually  fractures  of 
malleable  cast  iron  show  black  centers  and  thin  white  rims  or 
bands  around  the  outer  edge.  This  outer  band  is  practically  pure 
iron  due  to  the  burning  out  of  the  carbon  of  the  outer  portion  of 
the  casting. 

Malleable  cast  iron  is  especially  valuable  and  is  used  very 
largely  for  railroad  work.  At  one  time  malleable  cast  iron  was 
used  extensively  for  couplers,  but  now  steel  castings  are  used. 
Indications  are  that  gray  iron  is  being  replace-d  by  malleable  iron, 
while  on  the  other  hand  malleable  iron  is  being  replaced  by  cast 
steel.  Malleable  iron  is  used  extensively  for  parts  of  agricultural 
machinery  and  for  many  other  purposes  to  which  it  is  especially 
adapted. 

Welding  of  Malleable  Iron. — The  correction  of  flaws  in 
malleable  castings  by  the  arc  welding  process  effects  very  large 
savings  in  the  foundry.  Such  welding  is  always  done  after  the 
casting  is  annealed  and  made  into  a  malleable  casting.  Properly 
annealed  castings  will  show  just  a  thin  skin  of  white  iron  on  the 


IRON,  STEEL  AND  NON-FERROUS  METALS         155 

outer  edge.     The  annealed  section  is  essentially  low  carbon  cast 
steel. 

The  work  may  be  welded  with  either  the  carbon  or  metallic  elec- 
trode process.  Due  to  the  thinness  of  the  annealed  section  a  cur- 
rent as  low  as  consistent  for  good  fusion  is  used. 

If  the  casting  is  to  be  machined  in  the  welded  section,  it  is  rean- 
nealed.  This  is  usually  necessary  owing  to  the  fact  that  the  heat 
of  the  arc  will  in  effect  reverse  the  annealing  process.  That  is, 
the  carbon  which  was  set  free  as  graphite  by  the  annealing  is 
dissolved  in  the  iron  again  when  the  metal  becomes  molten  in  the 
heat  of  the  arc.  The  carbon  in  combination  with  the  iron  makes 
the  casting  hard.  In  some  cases,  such  as  the  welding  of  heavy 
sections,  the  same  methods  as  outlined  for  gray  iron  welding  are 
also  required  for  malleable  castings. 

Until  recently  it  has  been  a  difficult  matter  to  obtain  a  union 
between  the  added  metal  and  the  casting.  This  trouble,  however, 
has  been  eliminated  almost  entirely  by  using  a  coated  electrode  for 
metallic  arc  welding.  The  extreme  hardness  and  checks  of  the 
added  metal,  always  present,  at  least  in  the  first  layer  where  a  bare 
electrode  is  used,  are  largely  eliminated. 

Wrought  Iron. — In  the  production  of  wrought  iron  the 
common  practice  is  to  place  raw  material  such  as  scrap,  pig  iron, 
etc.,  in  an  open  hearth  furnace.  Heat  is  then  applied  and  as  the 
metal  becomes  pasty  the  mass  is  continually  raffled;  slagging 
agents  are  introduced  to  purify  and  deoxidize  the  charge.  After 
the  metal  has  been  raffled  sufficiently  the  pasty  mass  is  placed  in 
what  is  known  as  a  squeezer  and  as  much  of  the  slag  as  possible 
is  squeezed  out;  some  slag,  however,  always  remains.  The  me- 
chanical treatment  consists  of  squeezing  this  slag  out  of  the  metal 
and  rolling  it  into  bars  of  a  convenient  shape,  called  "merchant 
bars." 

The  quality  of  wrought  iron  is  a  function  of  its  purity,  i.  e.,  its 
freedom  from  every  substance  except  iron  or  ferrite.  Norway 
and  Swedish  iron  has  been  heretofore  the  purest  iron  ore  which 
could  be  obtained  in  commercial  quantities,  due  principally  to  the 
fact  that  the  ore  of  these  countries  does  not  contain  phosphorus 
or  sulphur.  The  traces  of  these  impurities  found  in  all  American 


156  ELECTRIC  ARC   WELDING 

iron  are  sufficient  to  render  it  inferior  in  quality  to  the  imported 
stock. 

Wrought  iron  is  used  as  a  base  in  the  manufacture  of  the  high- 
est quality  of  crucible  steels,  owing  to  its  purity.  The  tensile 
strength  of  wrought  iron  is  approximately  50,000  Ib.  per  sq.  in. 
It  is  malleable  and  does  not  harden  materially  when  it  is  subjected 
to  sudden  cooling. 

The  welding  of  wrought  iron  is  safe  and  legitimate  and  good 
practice.  No  bad  effects  from  the  heat  of  the  arc  flame  need  be 
feared  since  the  carbon  is  usually  less  than  0.12  per  cent,  which 
is  not  sufficient  to  give  any  hardening  effect  should  the  mass  of 
the  part  be  such  as  to  cause  sudden  cooling.  It  should,  however, 
be  remembered  that  the  metal  added  by  the  arc  process  is  cast 
metal  and  has  a  lower  degree  of  elasticity. 

Steel. — Steel  is  produced  either  by  the  Bessemer  or  the  open 
hearth  process.  It  is  known  as  acid  or  basic  steel,  according  to 
the  character  of  the  lining  used  in  the  Bessemer  converter  or  open 
hearth  furnace.  The  basic  lining  has  a  fluxing  action  which 
assists  in  removing  impurities  such  as  sulphur  or  phosphorus, 
whereas  in  the  acid  lined  furnaces  the  lining  has  little  influence 
in  the  removal  of  impurities ;  consequently  the  raw  material  used 
should  be  of  higher  purity  and  grade  to  begin  with.  Among  the 
elements  which  are  added  are:  carbon,  manganese,  nickel,  chro- 
mium, vanadium  and  tungsten.  In  ordinary  boiler  plate  and 
structural  shapes  the  controlling  elements  are  carbon  and  man- 
ganese. These  two  elements  are  the  only  ones  added.  The  carbon 
content  determines  the  tensile  strength,  while  the  manganese  is 
added  to  toughen  the  metal  and  prepare  it  for  the  mechanical 
treatment  in  the  rolls.  Boiler  plates  and  shapes  usually  contain 
from  0.2  to  0.3  of  1  per  cent  of  carbon  and  from  0.4  to  0.6  of  1 
per  cent  of  manganese. 

After  the  steel  has  been  given  the  desired  composition  it  may 
be  drawn  from  the  converter  into  the  ladles,  and  later  poured  into 
molds  to  make  steel  castings  or  it  may  be  drawn  from  the  con- 
verter into  ingot  molds  and  be  prepared  for  the  rolls.  If  the  steel 
is  to  be  used  for  forgings,  the  ingot  is  sheared  into  conveniently 
shaped  blocks  or  slabs  called  billets.  These  billets  are  then  sub- 
jected to  a  final  mechanical  treatment  in  the  drop  forging  ma- 


IRON,  STEEL  AND  NON-FERROUS  METALS         157 

chine.  Plates  and  shapes  are  castings  of  steel  which  have  been 
subjected  to  mechanical  treatment  in  the  rolls. 

The  distinguishing  and  active  element  of  steel  is  carbon.  With 
increase  in  carbon,  the  hardness  increases,  as  does  its  tensile 
strength,  but  the  ductility  (elongation  or  stretch)  decreases. 
Carbon  is  the  element  which  confers  upon  iron  the  ability  to 
harden  when  cooled  suddenly  from  a  cherry  red  heat,  as  by 
quenching  in  water  or  oil.  The  degree  of  hardness  that  can  be 
obtained  will  vary  with  the  amount  of  carbon  contained  in  the 
iron.  Mild  steel  below  two-tenths  of  one  per  cent  will  be  affected 
but  little  by  quenching,  while  steel,  with  five-tenths  of  one  per 
cent  or  more,  can  be  made  extremely  hard  and  brittle  by  sudden 
cooling. 

At  any  time  hardened  steel  may  be  returned  to  its  former  con- 
dition of  softness  by  the  well-known  process  of  annealing,  by 
reheating  to  the  same  cherry  red  heat  and  slowly  cooling.  As 
desired,  various  degrees  of  hardness  may  be  obtained  according 
(1)  to  the  percentage  of  carbon  in  the  steel,  and  (2)  the  rate  of 
cooling.  To  relieve  strains  caused  by  the  rapid  cooling,  the  hard- 
ening is  usually  "tempered"  by  heating  to  a  much  lower  tempera- 
ture and  again  quenching. 

The  heat  treatment  of  steel  is  a  broad  subject,  but  it  consists 
essentially  of  changing  the  crystalline  structure  of  the  steel  with- 
out changing  its  chemical  composition  in  order  to  get  certain 
desirable  properties.  Neglecting  the  effect  of  heat  treatment  the 
physical  properties  of  cast  steel  are  determined  by  the  kind  and 
amount  of  the  several  impurities  which  are  contained  in  the  metal. 
Impurities  of  various  combinations  are  used  to  get  certain  char- 
acteristics in  the  steel  which  seem  to  meet  the  requirements  of  the 
service  demanded  of  the  casting.  While  there  is  almost  an  un- 
limited number  of  combinations  which  may  be  obtained,  the 
ordinary  steel  foundry  uses  a  relatively  limited  number  as  com- 
pared to  the  possible  combinations.  Each  element  produces  its 
characteristic  effect  on  the  metal,  but  the  effect  on  the  tensile 
strength,  ductility,  toughness  and  malleability  is  not  necessarily 
proportional  to  the  quantity  of  the  added  element  over  a  very 
wide  range. 

It  is  more  difficult  to  obtain  sound  steel  castings  than  sound 


158  ELECTRIC  ARC  WELDING 

iron  casting,  since  the  shrinkage  of  steel  is  greater  than  of  cast 
iron,  and  checking  is  therefore  more  liable  to  occur.  Blow  holes, 
or  gas  bubbles,  enclosed  in  the  body  of  the  metal  are  especially 
liable  to  develop  in  mild  steel  castings. 

General  Effects  of  Impurities. — The  following  is  a  typical 
analysis  of  steel  castings : 

Element  Percentage 

Carbon    0.35 

Silicon ; .  0.40 

Manganese     0.80 

Phosphorus   0.05 

Sulphur    0.05 

The  properties  ordinarily  desired  in  steel  are  strength  and 
ductility.  Carbon  is  the  most  important  strengthener.  It  will  in- 
crease the  strength  of  the  steel  with  the  least  decrease  in  ductility. 

Silicon  causes  brittleness  if  a  high  percentage  is  present  Jn  iron 
or  steel.  About  the  largest  amount  present  in  any  commercial 
cast  steel  is  ^2  of  1  per  cent. 

Phosphorus  is  undesirable  in  any  quantity  in  steel  and  is  elimi- 
nated to  as  great  an  extent  as  possible.  It  causes  "cold  short"  or 
brittleness. 

Sulphur,  like  phosphorus,  is  undesirable  in  steel.  It  causes 
"hot  short"  or  brittleness  when  the  metal  is  red  hot  or  hotter. 

Manganese  helps  to  remove  the  phosphorus  and  sulphur;  it 
slags  these  two  elements  out  of  the  metal.  If  manganese  is  pres- 
ent up  to  about  5  per  cent  it  imparts  desirable  properties  to  steel, 
such  as  ductility  and  toughness.  Between  \y2  per  cent  and  Sy2 
per  cent  it  has  an  embrittling  action.  If  present  from  10  to  15 
per  cent  it  again  produces  a  tough  ductile  metal,  resisting  abra- 
sion, etc. 

Nickel  increases  the  tensile  strength  of  steel  without  impairing 
the  elasticity.  Nickel  steel  does  not  rust  as  easily  as  steel  without 
the  nickel.  The  amount  used  varies  from  a  small  per  cent  up  to 
3.5  per  cent. 

Vanadium  is  similar  to  nickel  in  its  effect  on  steel.  It  is  usually 
present  from  0.15  to  0.35  per  cent. 

Chromium  is  similar  to  manganese  in  its  effect  on  steel.  The 
amount  of  chromium  varies  according  to  the  purpose  for  which 


IRON,  STEEL  AND  NON-FERROUS  METALS         lS9 

the  steel  is  to  be  used.  Chromium  has  the  property  to  a  limited 
extent  of  acting  as  a  self-hardener  when  used  in  correct  amounts. 
Tungsten  is  used  in  the  manufacture  of  high-speed  steels. 
Tungsten  steel  has  the  property  of  retaining  its  hardness  at  high 
temperatures.  Its  composition  is  shown  in  the  following  table : 

Element  Percentage 

Carbon    0.40  to    2.19 

Chromium  or  Manganese 00  to    6.00 

Tungsten  or  Molybdenum , 3.44  to  24.00 

Silicon    21  to    3.00 

In  order  to  have  a  reasonably  definite  understanding  of  the 
structure  of  a  steel  casting,  the  history  of  the  steel  from  the  time 
it  is  originated  in  the  converter  until  it  becomes  a  cold  casting 
should  be  investigated.  Briefly,  it  may  be  stated  that  at  the  instant 
the  point  is  reached  in  the  conversion  process  at  which  all  of  the 
impurities  have  been  removed,  which  are  removable  in  practice, 
the  metal  in  the  converter  contains  ferrite,  and  traces  of  silicon, 
phosphorus  and  sulphur.  The  manganese,  carbon  and  any  other 
element  which  may  be  desired  is  then  added  to  the  molten  metal. 
The  relationship  or  manner  of  combination  of  the  elements  con- 
tained in  the  metal  between  the  time  it  exists  in  the  ladle  as  molten 
metal  and  the  state  of  a  cooled  casting  goes  through  several 
changes.  These  changes,  so  far  as  the  silicon,  phosphorus  and 
sulphur  are  concerned,  may  be  neglected,  since  the  rate  of  cooling 
has  practically  no  effect  upon  the  relationship. 

If  the  metal  is  suddenly  cooled  from  a  point  within  the  tem- 
perature range  in  which  any  of  these  changes  take  place,  the 
combination  of  the  elements  existing  at  the  time  the  cooling 
occurred  would  continue  to  exist.  In  other  words,  the  normal 
cooling  process  may  be  stopped  at  any  stage,  and  a  different 
structure  obtained  at  each  point  with  a  corresponding  difference  in 
physical  characteristics  of  the  metal.  The  heat  treatment  of  cast 
steel  amounts  simply  to  a  reversal  of  the  changes  outlined  above; 
that  is,  raising  the  temperature  of  the  casting  until  the  desired 
structure  is  produced,  then  fixing  it  at  that  point. 

Weldability  of  Steel  Containing  Impurities. — Little  is 
known  at  the  present  time  regarding  the  weldability  of  steel  con- 
taining the  impurities  given  above  when  present  in  their  usual 


160  ELECTRIC  ARC   WELDING 

amounts  when  the  electric  arc  welding  process  is  used.  It  is 
known,  however,  that  steel  containing  0.5  per  cent  or  more  of 
carbon  is  subject  to  "burning"  at  much  lower  temperatures  than 
low  carbon  steels.  This  fact  can  readily  be  observed  in  arc  weld- 
ing practice,  the  tendency  being  toward  "burnt"  metal  in  the  weld. 
The  observations  which  have  been  made  up  to  the  present  time 
seem  to  indicate  that  the  tendency  toward  "burning"  shown  in 
steels  of  comparatively  high  carbon  content  is  the  only  consider- 
able effect  which  is  produced  on  the  weldability  by  the  presence 
of  any  of  the  impurities  in  their  usual  amounts. 

The  intelligent  solution  of  welding  problems  in  cast  steel,  as  far 
as  the  metallurgical  part  is  concerned,  begins  with  a  study  of  the 
casting  to  determine  its  nature  and  its  characteristics.  The  weld- 
ing process  amounts  simply  to  the  addition  of  a  certain  amount  of 
cast  steel  of  a  given  composition  so  that  a  knowledge  of  the  be- 
havior of  the  metal  of  the  casting  as  well  as  of  the  metal  to  be 
added  when  subjected  to  the  temperature  of  the  arc  flame  permits 
us  to  predetermine  accurately  what  the  nature  of  the  complete  job 
may  be. 

The  photograph,  Fig.  80,  shows  a  number  of  blades  arc  welded 
in  a  large  cast  steel  distributing  wheel  for  a  hydro-electric  turbine 
at  Niagara  Falls ;  these  had  been  broken  by  an  obstruction  getting 
into  the  turbine.  This  should  give  some  conception  as  to  the  use- 
fulness of  the  process  in  repairing  fractured  cast  steel  castings. 

The  chemical  analyses  that  have  been  made  of  the  metal  de- 
posited in  the  weld,  using  a  bare  electrode,  show  that  most  of  the 
carbon  and  manganese  is  burned  out  in  traversing  the  arc.  How- 
ever, by  the  use  of  coated  electrodes  to  exclude  the  air  from  the 
metal  while  in  a  molten  state,  thus  preventing  oxidation  and  the 
loss  of  certain  constituent  parts  during  the  execution  of  the  weld, 
it  is  possible  to  deposit  metal  of  a  composition  approximately 
equal  to  that  of  the  part  being  welded. 

Welding  Steel  Forgings. — Forgings  are  simply  castings  of 
steel  which  have  been  subjected  to  mechanical  treatment  under  the 
hammer.  This  process  creates  compressive  strains,  and  as  the 
pressure  is  relieved  at  once  the  elasticity  of  the  metal  causes  it  to 
recover  somewhat  from  the  effect.  The  result  of  the  treatment  is, 
therefore,  superficial.  Hammering  is  comparatively  a  slow  proc- 


IRON,  STEEL  AND  NON-FERROUS  METALS 


161 


ess  of  reduction,  but  results  in  a  better  and  more  uniform  working 
of  thg  crystals  which  is  the  chief  reason  for  the  superiority  of 
hammered  over  rolled  metal.  In  regard  to  other  working  condi- 
tions concerning  the  hammering  process,  perhaps  the  most  impor- 
tant is  the  extra  control  over  the  operation  and  over  the  tem- 


FIG.  80— Fractured  Blades  Were  Welded  to  This  Cast  Steel  Turbine  Wheel 
by  Electric  Arc  Welding 

perature  at  which  the  work  is  finished.    These  things  can  be  con- 
trolled at  the  discretion  of  the  expert  forger. 

Drop  forgings  are  directly  comparable  with  steel  castings  ex- 
cept that  they  are  superior  in  quality  on  account  of  the  beneficial 
effect  produced  by  working.  There  is  a  large  variety  of  articles, 
such  as  parts  of  machinery,  etc.,  which  are  formed  by  this  means. 
The  process  consists  essentially  in  placing  a  piece  of  heated  metal 


162 


ELECTRIC  ARC   WELDING 


between  two  dies.  The  metal  is  then  squeezed  into  these  dies  until 
it  has  assumed  the  proper  shape.  Sometimes"  more  than  one  set 
of  dies  are  required  to  complete  the  finished  article. 

Aside  from  the  correction  of  small  flaws  before  the  forging 
leaves  the  forge  shop,  the  principal  application  of  the  arc  welding 


FIG.  81— The  Shaft  for  an  Excitor  Turbine  Was  Welded  by  Metallic  Arc 
Welding  Apparatus 

process  is  in  the  welding  of  worn  and  broken  parts.  The  metal- 
lurgical problems  involved  in  the  welding  of  forgings  are  the  same 
as  those  in  the  welding  of  cast  steel  so  far  as  the  character  of  the 
metal  in  the  weld  is  concerned. 

In  forgings,  however,  the  product  has  passed  through  a  process 
of  mechanical  treatment  which  improves  its  quality  for  certain 
purposes  beyond  that  of  cast  steel.  The  result  of  this  mechanical 
treatment  is  greater  compactness  of  the  structure  with  a  resultant 


IRON,  STEEL  AND  NON-FERROUS  METALS         163 

increase  in  toughness.  Therefore,  the  welded  piece  will  consist 
of  two  grades  of  metal;  the  original  metal  which  has  received 
mechanical  treatment  and  the  metal  added  by  the  welding  process 
which  has  not  received  mechanical  treatment.  In  general,  the 
metal  added  by  the  welding  process  will  always  have  the  charac- 
teristics of  cast  steel  and  the  original  unmelted  part  will  always 
have  the  properties  of  mechanically  treated  metal.  The  metal  in 
the  weld  may  be  hard  or  soft,  of  high  or  low  tensile  strength,  but 
it  will  never  have  the  toughness  to  resist  the  tendency  to  crack  in 
bending  to  the  same  degree  as  the  mechanically  treated  metal. 

Up  to  the  present  time  no  cast  steel  has  been  produced  which 
has  all  of  the  properties  to  the  same  degree  as  are  found  in  any 
given  piece  of  forged  or  rolled  metal.  This  limitation  of  any 
welding  process  in  which  steel  is  melted  should  never  be  lost  sight 
of  in  welding  practice. 

The  nature  of  the  weld  and  a  study  of  the  stresses  imposed 
upon  the  part  will  govern  the  extent  of  application  of  the  process 
to  such  parts.  In  a  great  number  of  instances  forged  or  rolled 
parts  can  be  safely  and  advantageously  welded  by  the  metallic  arc. 
Fig.  81  shows  a  welded  shaft  of  an  excitor  turbine  for  a  large 
hydro-electric  turbo-generator,  which  has  been  completely  broken. 
The  weld  is  located  between  the  two  shoulders  on  the  shaft  at  the 
end  of  the  bearing  case. 

The  application  of  the  arc  welding  process  on  steel  plates  and 
shapes  which  are  produced  by  the  reduction  of  steel  ingots  in  rolls 
is  similar  in  every  way  to  its  application  to  steel  forgings.  This 
is  due,  of  course,  to  the  fact  that  plates,  structural  shapes,  etc., 
belong  to  that  class  of  products  which  have  been  subjected  to  me- 
chanical treatment. 

General  Conclusions 

From  the  foregoing  several  general  conclusions  may  be  drawn : 

(1)  The  tensile  strength  of  the  cast  steel  in  the  weld  may  be 
made  less  than,  greater  than,  or  equal  to  the  tensile  strength  of  the 
metal  in  the  original  section.     This  is  true  for  commercial  plate 
only. 

(2)  The  metal  may  be  harder  or  softer  than  the  metal  in  the 
original  piece.    The  tensile  strength  of  the  metal  in  the  weld  will 


164  ELECTRIC  ARC   WELDING 

vary  with  the  hardness.     Burned  metal  is  neglected  in  this  con- 
clusion. 

(3)  The  elasticity  of  the  metal  in  the  weld  will  always  be  less 
than  the  elasticity  of  the  metal  in  the  original  plate. 

Thermal  Effect  of  Welding  Heat  on  Parent  Metal.— The 
effect  of  heat  on  the  material  being  welded  is  governed  largely 
by  the  rate  of  cooling  and  the  carbon  content.  The  rate  of  cool- 
ing will  be  determined  by  the  mass  of  work,  shape  of  the  work, 
and  by  the  manipulation  of  the  arc  by  the  operator.  The  rate  of 
cooling  may  be  different  in  different  parts  of  the  same  weld,  with 
a  corresponding  difference  in  character,  of  the  metal  in  different 
sections.  This,  of  course,  is  noticeable  more  in  the  higher  carbon 
steels  than  in  those  which  contain  around  0.10  per  cent  of  carbon. 

When  welding  steel  parts  containing  carbon  above  0.10  per  cent 
that  have  little  or  no  factor  of  safety  and  which  are  subjected  to 
alternate  stresses  the  effect  of  the  heat  must  be  considered,  even 
though  the  process  is  applied  only  to  the  extent  of  building  up  the 
part.  In  some  cases,  as  with  parts  vital  to  the  operation  of  ma- 
chinery, such  as  piston  rods,  crank  pins,  and  parts  of  similar  im- 
portance, it  is  advisable  to  anneal  after  welding.  An  example  of 
what  may  be  expected  from  the  effects  of  localized  heat  on  such 
parts  is  shown  in  Fig.  82  (Fig.  1)  which  is  the  result  of  an  investi- 
gation of  a  failed  locomotive  piston  rod  on  which  the  cross-head 
fit  had  been  built  up  by  the  metallic  arc  process.  This  photo- 
graphic reproduction  shows  the  area  of  added  metal  around  the 
circumference.  Between  it  and  the  larger  section  of  metal  in  the 
rod  is  an  area  of  metal,  scallop  shaped,  effected  by  the  heat.  This 
illustrates  the  condition  of  the  metal  in  the  rod  at  the  time  it 
failed.  Measurements  recorded  for  the  average  scleroscope  hard- 
ness of  the  section  shown  in  Fig.  1  (Fig.  82)  are: 

Added  Metal  49 

Dark  Heat-effected  Area 80 

Metal  in  the  Rod 50 

The  break  resulted  from  small  interior  checks  resulting  in  a 
detailed  fracture  which  developed  in  the  dark  heat-effected  area 
after  the  piston  rod  had  been  in  service  a  few  months. 

Figs.  2  and  3  (in  Fig.  82)  show  sections  taken  directly  opposite 
to  the  section  shown  in  Fig.  1.  These  sections  were  heated  to  1500 


IRON,  STEEL  AND  NON-FERROUS  METALS         165 

deg.  Fahr.  and  held  at  that  temperature  for  three  hours,  following 
which  the  section  shown  in  Fig.  2  (Fig.  82)  was  allowed  to  cool 
in  the  furnace,  then  polished  and  etched.  The  section  shown  in 
Fig.  3  (Fig.  82)  was  allowed  to  cool  in  the  air,  then  polished 
and  etched.  These  photographic  reproductions  show  that  the 


FIG.  82 — Sections  of  Piston  Rod  Built  up  by  Metallic  Arc  Showing  Effect 
of  Localized  Heat  and  Result  of  Annealing 

annealing  process  entirely  eliminated  the  hardened  area  illustrated 
in  Fig.  1  (Fig.  82). 

Measurements  recorded  for  the  average  scleroscope  hardness  of 
the  section  shown  in  Fig.  2  (Fig.  82)  are: 

Added  Metal  38 

Metal  in  the  Rod 55 

Measurements  recorded  for  the  avera'ge  scleroscope  hardness  of 
the  section  shown  in  Fig.  3  (Fig.  82)  are : 

Added  Metal  38 

Metal  in  the  Rod 57 

The  chemical  requirements  under  which  the  piston  rod  was 
purchased  were  as  follows : 

Element  Percentage 

Carbon— Not  less  than 0.38  or  over  0.52 

Manganese — Not  less  than 0.40  or  over  0.60 

Phosphorus — Not  over    0.045 

Sulphur— Not  over  0.05 


166  ELECTRIC  ARC   WELDING 

The  weld  was  made  with  a  bare  mild  steel  electrode,  which  ac- 
counts for  the  difference  in  the  degree  of  hardness  between  the 
added  and  the  original  material,  as  any  carbon  or  manganese  that 
may  have  been  in  the  electrode  material  was  burned  out  in  passing 
through  the  arc.  The  same  conditions  develop  where  other  auto- 
genous welding  processes  are  used,  and  in  some  cases  this  heat- 
effected  zone  may  penetrate  further  than  in  the  case  of  the  electric 
welding  process. 

It  is  not  the  intention  to  convey  the  idea  that  it  is  necessary  to 
anneal  all  such  parts  after  they  have  been  welded.  This  would 
not  be  consistent  with  everyday  practice.  As  a  matter  of  fact, 
most  work  of  this  class  is  done  without  annealing  and  with  com- 
paratively few  failures.  However,  alloy  steels,  and  especially  heat 
treated  steels,  are  sensitive  to  heat  treatment;  this  fact  must  not 
be  lost  sight  of. 

As  the  question  of  heat  effects  is  of  great  importance  and  has 
in  many  cases  formed  the  basis  of  weld  failures  the  results  of  an 
extensive  investigation  conducted  by  T.  D.  Sedwick,  engineer  of 
tests,  Chicago,  Rock  Island  &  Pacific  Railroad,  is  here  given.  It 
was  included  in  a  paper  read  before  the  American  Welding  So- 
ciety, Chicago  Section,  December  22,  1920. 

"In  case  of  poor  results  from  fusion  welding  shown  either  by 
laboratory  tests  or  actual  service,  the  inclination  is  to  attribute 
such  results  to  the  material  used,  the  method  of  making  the  weld, 
a  poor  operator,  or  the  contributing  effect  of  all  three  of  these 
factors. 

"But  there  are  other  points  that  enter  into  the  final  results,  and 
two  of  the  important  ones  are  as  follows : 

"First — Was  the  metal  in  the  casting  or  forging  in  such  a  physi- 
cal condition  that  it  was  fit  to  be  welded  and  afterwards  give  good 
service ;  did  the  metal  originally  fail  on  account  of  the  presence  of 
segregation  of  the  various  chemical  elements ;  did  it  contain  blow-- 
holes, porosity,  or  were  there  thermal  stresses  left  from  the  origi- 
nal forging  or  casting  operations ;  had  the  previous  service 
fatigued  the  metal  to  the  extent  that  it  was  inherently  weak  ? 

"Second — Was  the  original  metal  adjacent  to  the  weld  dele- 
teriously  affected  by  the  welding  operation  ? 

"Some  take  the  first  mentioned  factors  into  consideration,  but  I 


IRON,  STEEL  AND  NON-FERROUS  METALS         167 

do  not  believe  that  very  many,  particularly  the  shopmen,  give 
much  thought  to  any  action  which  may  take  place  on  the  original 
metal.  Tests  and  observations  made  on  failed  material  and  special 
test  specimens  have  shown  that  welds  fail  although  good  condi- 
tions prevail  in  all  other  respects. 

"Investigation  on  various  welds  has  shown  that  in  the  majority 
of  the  cases,  especially  in  certain  classes  of  material,  the  welding 
heat  or  the  process  of  preheating  has  affected  the  metal  in  the 
sections  being  welded,  causing  a  transformation  of  the  physical 
structure  of  the  steel,  and  in  case  of  localized  high  temperatures 
the  main  body  of  the  material  absorbs  the  heat  so  fast  that  there 
results  a  quenching  action  on  the  heated  metal.  In  the  majority 
of  instances  the  extreme  hardening  action  will  be  localized  near 
the  surface  immediately  adjacent  to  the  added  metal.  In  some 
cases  of  preheating  it  has  been  shown  that  the  high  temperature 
causes  a  change  in  the  physical  structure  of  the  metal,  and  while  it 
is  not  usually  so  localized  as  in  the  case  of  the  action  of  the  weld- 
ing heat  alone,  thermal  stresses  are  set  up  in  addition  to  those 
created  by  the  heat  of  the  welding  process.  These  conditions 
have  been  found  in  material  of  thick  sections  where  the  heat 
.would  not  be  readily  absorbed  throughout  the  section  and  where 
the  chemical  content,  especially  the  carbon,  was  such  that  it  ren- 
dered the  metal  readily  susceptible  to  structural  changes,  resulting 
in  a  hardened  condition. 

"A  great  many  tests  were  made  to  demonstrate  to  shopmen, 
that  in  the  majority  of  cases  proper  annealing  should  be  done 
after  the  weld  has  been  completed  and  that  a  thorough  annealing 
would  improve  the  physical  condition  of  the  metal,  thereby  causing 
it  to  render  better  service;  this  thorough  annealing  to  be  made 
by  placing  the  metal  in  a  furnace  and  giving  it  a  soaking  heat  and 
then  cooling  it  so  that  the  whole  mass  could  adjust  itself  to  a  uni- 
form condition  throughout. 

"The  idea  of  causing  a  self  or  automatic  annealing  to  take  place 
by  preheating  is  going  at  the  proposition  backwards  and  trusting 
to  luck  that  we  have  not  done  more  damage  than  good.  It  is 
necessary  at  times  to  preheat  to  take  care  of  the  shrinkage  strains 
which  might  be  set  up  in  certain  sections  during  the  cooling  after 
welding.  It  is  advisable  after  this  has  been  done  to  follow  out  a 


168  ELECTRIC  ARC   WELDING 

thorough  annealing  program.  In  this  way  any  strain  or  hardened 
condition  that  has  been  set  up  by  preheating,  or  by  the  welding 
heat,  will  be  eliminated  and  we  will  then  have  a  product  the  service 
of  which  will  depend  mainly  on  the  quality  of  the  material  in  the 
weld,  and  the  perfection  of  the  weld. 

"There  are  certain  zones  in  any  torch  flame  that  are  of  a  higher 
temperature  than  others,  and  as  it  too  often  happens  that  a  suffi- 
cient length  of  time  is  not  taken  in  preheating  to  permit  a  soaking 
heat,  more  or  less  locally  heated  areas  are  produced  that  multiply 
the  thermal  stresses  not  eliminated  during  the  subsequent  period 
of  cooling. 

"In  the  majority  of  the  shops,  especially  the  larger  shops,  where 
special  annealing  furnaces  have  not  been  installed,  there  are 
always  some  furnaces  of  sufficient  size  in  which  at  least  the 
smaller  castings  and  forgings  could  be  annealed  and  this  anneal- 
ing could  be  done  at  a  comparatively  low  cost.  At  the  close  of 
the  day,  as  space  is  unoccupied  by  the  regular  work  of  the  shops, 
the  welded  material  could  be  placed  in  the  furnace  and  be  annealed 
over  night  without  any  material  increase  in  the  cost  of  fuel.  This 
plan  would  not  check  production  of  the  regular  work. 

"Too  little  attention  is  given  to  annealing  in  -general  even  in 
cases  where  no  welding  is  done.  In  reclamation  plants  where  old 
material  is  re-worked,  a  worn  out  or  failed  forging  will  be  re- 
forged.  When  originally  forged  thermal  stresses  may  have  been 
set  up  in  this  material  and  not  removed,  or  the  material  may  have 
been  overheated  or  even  burnt.  Later,  during  its  actual  service, 
fatigue  stresses  and  unsatisfactory  physical  structure  may  have 
been  produced.  On  reforging,  further  stresses  may  be  set  up  and 
then  without  annealing  to  refine  the  grain  and  remove  these 
stresses  the  forging  will  be  returned  to  service.  While  it  may 
give  some  service,  if  we  had  gone  a  little  further  and  treated  it 
properly,  the  extended  service  in  my  opinion  would  have  been 
sufficiently  great  to  more  than  justify  any  extra  trouble  or  expense 
involved  in  a  final  annealing  after  forging.  The  same  thought 
applies  to  welding  of  failed  material. 

"There  are  a  great  many  misconceptions  of  the  process  of  an- 
nealing and  a  great  many  shopmen  fail  to  observe  the  rule  that  it 
requires  time  for  a  piece  of  steel  to  adjust  itself  to  the  annealing 


IRON,  STEEL  AND  NON-FERROUS  METALS 


169 


temperature  and  be  uniformly  heated  throughout.  For  instance, 
on  one  particular  forging  which  the  workman  was  instructed  to 
anneal  thoroughly  he  advised  that  he  was  doing  so.  But  later  it 
was  found  that  he  was  simply  sticking  the  forging  into  a  black- 
smith fire  so  that  the  welded  area  was  buried  in  the  fire.  Under 
such  conditions,  while  the  extremely  localized,  highly  affected 
areas  will  be  improved,  minor  stresses  will  be  set  up  back  along 
the  forging.  To  do  the  job  right  the  forging  as  a  wrhole  should 
have  been  subjected  to  the  annealing  heat. 

"With  such  methods  it  is  hardly  fair  to  expect  100  per  cent 
service  out  of  material  to  which  we  have  added  or  in  which  we 


FIG.  82- A — Crank  Pin;  Metal  Added  with  Electric  Arc;   No   Preheating 

of  Any  Kind 

have  produced  unsatisfactory  conditions  rather  than  reduced 
them.  I  am  not  looking  at  this  matter  from  a  strictly  theoretical 
standpoint ;  the  tests  and  the  various  failed  material  which  have 
come  to  our  attention  justify  these  remarks. 

"A  few  etched  sections  were  made  in  an  investigation  to  de- 
termine, if  a  system  of  preheating  could  be  developed  to  eliminate 
the  hardened  zones  or  heat  affected  areas  created  either  through 
the  preheating  or  the  welding  heat. 

"Fig.  82-A  is  a  crank  pin,  on  which  no  preheating  of  any  kind 
was  done.  The  scleroscope  hardness  on  the  added  metal  was.  33, 
on  the  hardened  zone  58,  and  on  the  rod  proper  46.  The  metal 
was  added  with  an  electric  arc.  Fig.  82-B  shows  the  previous 
piece  after  annealing,  the  added  metal  showing  a  hardness  number 
of  34,  and  the  pin  metal  proper  45.  Fig.  82-C  is  a  piece  of  crank 


170  ELECTRIC  ARC   WELDING 

pin  steel  to  which  the  patch  was  made  after  preheating  the  parent 
metal  with  the  arc,  resulting  in  the  hardness  numbers  of  35  in  the 
added  metal,  59  in  the  hardened  zone,  and  47  in  the  rod.  The 
metal  was  added  with  the  electric  arc.  After  annealing,  the  hard- 
ened zones  were  removed;  the  hardness  number  in  the  added 
metal  was  35  and  in  the  rod  45. 

"Another  piece  of  the  pin  was  preheated  in  the  blacksmith  fur- 
nace and  metal  added  by  the  electric  process ;  in  this  case  the  hard- 
ness number  in  the  added  metal  was  34,  in  the  hardened  zone  of 
the  pin  59,  and  in  the  body  of  the  pin  46.  After  annealing,  as  in 
the  previous  instances,  the  hardened  area  was  eliminated,  resulting 


FIG.  82-B— Crank  Pin;  Metal  Added  with  Electric  Arc  after  Preheating 
in   Blacksmith  Furnace.    Annealed  after   Metal   Was   Added 


in  a  hardness  number  in  the  added  metal  of  34  and  in  the  rod 
of  45. 

"A  pin  was  preheated  with  the  arc,  but  no  metal  added,  result- 
ing in  a  clearly  defined  hardened  zone  with  a  hardness  number  of 
64,  the  body  of  the  rod  showing  44.  After  annealing  this  piece  the 
hardness  was  uniformly  45  out  to  the  edge  of  the  piece. 

"Metal  was  added  around  the  section  of  a  locomotive  frame 
with  the  electric  arc,  without  preheating.  The  metal  was  added  in 
three  layers  with  the  idea  that  the  succeeding  layers  might  exert 
an  annealing  action  on  the  affected  area.  The  hardness  number  in 
the  added  metal  was  34,  in  the  affected  area  57,  and  with  the 
parent  metal  47.  After  annealing  this  piece  the  affected  zone  was 
removed.  The  same  frame  member  was  preheated  with  the 
electric  arc  and  metal  again  added  in  three  layers,  as  in  the  former 


IRON,  STEEL  AND  NON-FERROUS  METALS         1?1 

case,  without  showing  any  improvement  in  the  hardening  effect  of 
the  welding  heat. 

"Attention  is  called  to  the  extension  of  the  action  of  the  arc 
ahead  of  the  added  metal,  which  may  be  observed  in  these  photo- 
graphs. It  will  be  noted  that  the  hardened  zone  extends  about  the 
same  distance  in  front  and  back  of  the  points  where  the  welding 
operation  starts  and  stops  as  it  does  beneath  the  weld.  In  a  great 
many  cases,  in  fact  in  the  majority,  it  appears  that  a  fracture  will 
start  by  an  initial  check  through  the  affected  zone  immediately 


;: 
pe  Hardness    . 


FIG.  82-C— Crank  Pin;  Metal  Added  by  Electric  Arc  After  Preheating 

with  Arc 


back  of  or  in  front  of  the  added  metal,  although  there  have  been 
cases  that  unquestionably  were  detail  fractures  starting  from  the 
area  underneath  the  added  metal. 

"Fig.  82-D  is  a  piston  rod  which  was  preheated  according  to  the 
regular  practice  and  metal  added  by  the  oxy-acetylene  process, 
producing  the  affected  zones  shown.  The  hardness  of  the  added 
metal  in  this  case  was  32,  in  the  affected  zones  53,  and  in  the  rod 
proper  44.  On  annealing  this  piece  the  affected  zones  were  re- 
moved ;  the  added  metal  then  showed  a  hardness  of  34  and  the  rod 
44.  Fig.  82-E  shows  the  same  affected  zones  when  the  metal  was 
added  by  the  oxy-acetylene  process  without  preheating.  The 
added  metal  shows  a  hardness  of  32,  the  affected  zones  53,  and  the 


172  ELECTRIC  ARC   WELDING 

body  of  the  rod  42.  On  annealing,  the  affected  areas  were  elimi- 
nated, resulting  in  a  hardness  number  in  the  added  metal  of  35  and 
in  the  rod  of  45. 

"I  do  not  want  to  leave  the  impression  that  all  welds  fail  on 
account  of  the  structural  changes  due  to  the  heating,  or  that  I  am 
advocating  not  doing  any  welding  at  all,  or  that  I  am  in  favor  of 
any  one  particular  process  of  welding.  All  the  various  methods  of 
welding  have  their  proper  fields,  and  a  great  deal  of  profitable 
work  can  be  done  with  them.  However,  if  the  points  mentioned 
are  -taken  into  consideration  by  the  party  laying  out  the  welding 
work,  our  welds  will  show  fewer  failures. 


Soleroscope  Hardness 


FIG.  82-D — Piston  Rod;  Preheated  in  Regular  Practice  and  Metal  Added 
with  Oxy-Acetylene 

"In  the  welding  of  steel  plates,  shapes,  etc.,  the  conditions  out- 
lined above  do  not  exist,  at  least  with  commercial  plate  up  to 
l/2  in.  thick.  This  is  due  to  the  fact  that  the  cooling  curve  is  not 
so  sharp;  that  is,  the  difference  in  temperature  over  a  given  area 
within  the  vicinity  of  the  weld  is  much  less  than  in  the  case  of 
thick  sections  and  heavy  mass. 

"An  intelligent  analysis  of  the  problems  encountered  in  the 
service  required  of  a  given  joint,  together  with  an  application  of 
established  welding  methods,  will  leave  no  excuse  for  the  failure 
of  a  joint  which  has  been  calculated  to  hold.  The  experienced 
welder  does  not  guess ;  he  knows  what  the  joint  will  do.  The  suc- 
cess of  the  electric  arc  welding  process,  like  any  other  manufac- 
turing process,  depends  ultimately  on  the  exercise  of  human  skill 
and  ingenuity.  These  factors  are  by  far  the  most  important  to  be 


IRON,  STEEL  AND  NON-FERROUS  METALS         173 

considered.  The  apparatus  itself  is  inanimate,  but  in  skillful 
hands  under  the  direction  of  an  ingenious  mind,  it  will  take  a  fore- 
most place  among  the  machines  which  produce  an  improved 
product  at  a  lower  cost." 

Weldability  of  Other  Metals. — Chrome  steels  are  weldable, 
if  the  percentage  of  carbon  does  not  bring  them  within  the  cate- 
gory of  hard  steels,  which  is  usually  the  case.  The  difficulties  en- 
countered are  similar  to  those  mentioned  heretofore  in  connec- 
tion with  high  carbon  steel. 

High  Manganese  steel  can  be  welded  by  the  metallic  arc  proc- 
ess, providing  a  protecting  slag  is  used  to  protect  the  metal  from 


Seleroscope  Hardness 


FIG.  82- E— Piston  Rod;  Metal  Added  with  Oxy-Acetylene,  No  Preheating 

the  atmosphere.  It  has  so  far  been  very  difficult  to  obtain  elec- 
trode materials  of  a  high  manganese  content,  and  for  this  reason 
no  great  amount  of  welding  with  high  manganese  steel  has  been 
done. 

Nickel  steel  may  be  welded,  providing  the  nickel  content  is  not 
too  high.  Pure  nickel  cannot  be  welded  commercially  on  account 
of  the  absorption  of  gas  by  the  metal  when  melted  by  the  arc. 
The  deposit  is  porous  and  possesses  practically  no  strength. 
Some  welding  has  been  done  by  heating  the  metal  in  a  reducing 
atmosphere,  such  as  a  hydrogen  flame.  On  account  of  this  diffi- 
culty nickel  steel  electrodes  have  not  been  very  satisfactory. 

Non-ferrous  metals  as  commercially  used  are  more  or  less  diffi- 
cult to  weld  by  the  electric  arc. 


174  ELECTRIC  ARC   WELDING 

Brasses  are  not  easily  welded  on  account  of  the  vaporization  of 
the  zinc  content  when  subjected  to  the  temperature  of  the  electric 
arc.  The  addition  of  metal  to  brass  is  possible,  but  the  use  of  a 
brass  rod  as  an  electrode  material  is  not. 

Bronzes  which  have  a  considerable  lower  percentage  of  zinc 
can  be  welded  without  difficulty  by  the  carbon  arc  or  with  the 
metallic  arc,  provided  the  percentage  of  zinc  and  tin  is  low  in 
the  electrode  material. 

Aluminum  can  be  welded  by  the  arc  after  a  fashion,  but  not 
as  a  commercial  proposition. 

In  welding  with  almost  any  of  the  non-ferrous  metals  it  is  neces- 
sary to  reverse  the  polarity  on  account  of  the  comparatively  low 
melting  point  of  such  metals,  so  that  the  electrode  will  be  positive 
and  the  workpiece  negative. 


X 

APPLICATION  OF  ARC  WELDING  TO  RAILROADS 
AND  STRUCTURAL  ENGINEERING 

The  usefulness  and  economy  of  the  arc  welding  process  has 
been  demonstrated  in  many  industries  to  an  extent  such  as  to 
insure  its  permanency  and  make  its  future  exceedingly  bright. 
During  the  World  War  when  labor  and  material,  especially  iron 
and  steel,  were  exceedingly  scarce  and  in  some  cases  impossible 
to  secure  on  short  notice  to  meet  emergencies,  every  industry  was 
compelled  to  use  every  modern  means  to  effect  economical  pro- 
duction, and  to  this  end  no  process  enjoyed  more  merited  recog- 
nition in  the  fabrication  and  reclamation  of  iron  and  steel  than 
that  of  autogenous  welding. 

While  all  forms  of  autogenous  welding  share  in  this  respect, 
the  metallic  arc  process,  being  the  least  used  prior  to  the  war, 
received  almost  national  attention  as  a  result  of  the  miraculous 
achievements  by  its  use,  and  as  a  result  the  progress  in  the  art 
was  much  more  rapid  than  would  have  been  the  case  in  normal 
times.  In  many  cases  the  exact  method  of  applications  had  to  be 
developed.  A  few  of  the  many  advantageous  applications  of  the 
process,  together  with  the  methods  employed,  are  shown  on  the 
following  pages. 

Among  the  first  commercial  applications  of  the  arc  welding 
process  on  the  railroads  was  that  of  repair  work  and  flue  weld- 
ing; i.  e.,  the  welding  of  the  boiler  tubes  to  the  tube  sheet  in  loco- 
motive boilers.  In  this  field  the  process  has  been  constantly  ex- 
panded and  at  the  present  time  it  is  used  extensively  by  many  of 
the  large  railroads. 

In  a  number  of  cases  the  success  of  the  process  for  joining 
steel  plate  has  been  so  thoroughly  demonstrated  that  riveted  seams 
in  locomotive  fireboxes  have  been  entirely  eliminated,  and  many 
such  fireboxes  are  in  successful  operation.  That  these  results 

175 


176 


ELECTRIC  ARC   WELDING 


have  been  obtained  is  due  to  the  development  of  the  art  and  its  ap- 
plication and  not  to  any  new  fundamental  discoveries.  There  have 
been,  however,  great  strides  in  the  refinement  of  the  equipment, 
electrode  material,  methods  of  application ;  and  last  but  not  least 
skilled  operators  have  been  produced,  which  is  especially  vital  in 
boiler  welding. 

Completely  Welded  Fireboxes. — In  the  application  of  new 
fireboxes,  the  seams  of  which  are  to  be  arc  welded,  the  door  sheet 


i  it 

g  — H  k—  fain  force 


Crown  -Seam 
Connecting 
Flue  -Sheet. 


Connec-fing 
U       Door  Sheet 


FIG.  83 — Preparation  of  Door  and  Flue   Sheet,   Crown   Seams  and   Side 
Seams  for  Arc  Welding  New  Firebox 

and  the  flue  sheet  are  prepared  with  flanges  of  not  less  than  2l/2 
in.  as  shown  in  Fig.  83.  The  one-piece  sides  and  crown  sheet  are 
set  and  securely  bolted  to  the  mud  ring.  The  door  sheet  and  flue 
sheet  are  then  likewise  set  in  place.  The  edges  of  all  sheets  should 
be  beveled  to  a  45  deg.  angle  from  the  fire  side,  leaving  an  open- 
ing between  all  edges  to  be  joined  of  approximately  %  in. 

When  starting  welds  on  cold  massive  parts  a  greater  current 
density  or  heat  is  required  for  proper  fusion  than  will  be  the  case 
after  the  work  has  warmed  up.  To  avoid  readjustment  of  heat 
it  is  good  practice  to  start  the  weld  with  a  smaller  size  electrode 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       177 


than  that  for  which  the  heat  is  adjusted  and  when  the  part  warms 
up  change  from  the  smaller  electrode  to  the  next  larger  size. 
When  it  is  possible,  the  top  seams  of  a  new  firebox  should  be 


\here 


First:  We/ct  Section/,  r*>xt  Wefd  Section  2 
Sfarf  at  B,  and  tfrish  at  A.  Men 
Sec  f ion  J,  sfarf/ngaf  C,  and  finish 
of  B  etc.  unff/Seam  is  finished 

FIG.  84— Method  of  Procedure  in  Welding  the  Four  Vertical  Seams  on  a 

Firebox 

welded  with  the  box  lying  on  its  side.  This  will  avoid  overhead 
welding  and  will  place  the  crown  seams  in  a  vertical  position 
where  they  may  be  welded  from  the  fire  side,  as  shown  by  sec- 


t 

6 

t 

1 

t 

8 

t 

1 

I 

\ 

t 

Mote:  hirst  section  To  be 
obou'f"  3"  long 

t 

3 

t 

4 

t 

5 

FIG.  85 — Weld  in  Numerical  Order  and  in  Direction  as  Shown  by  Arrows 

tional  view,  Fig.  84.     The  crown  seams  should  be  slightly  rein- 
forced on  the  water  side. 

The  four  vertical  seams  are  welded  with  the  firebox  in  the 


178  ELECTRIC  ARC   WELDING 

normal  position.  In  order  to  avoid  unnecessary  distortion  of  the 
sheets  each  seam  is  welded  in  sections  in  the  order  shown  in  Fig. 
85.  The  first  section  welded  should  be  approximately  3  in.  long 
and  should  be  finished  flush  before  starting  the  second  section. 
The  second  and  remaining  sections  may  be  as  long  as  10  in.  In  all 
cases  each  section  should  be  finished  at  least  flush  before  starting 
another.  The  finished  weld  should  be  reinforced  approximately 


FIG.  86— Side  Sheet  Joints  Welded  with  Electric  Arc 

%  in.  Views  of  side  and  crown  sheet  arc  welding  are  shown  in 
Figs.  86  and  87. 

The  size  of  the  electrode  to  be  used  for  firebox  plate  thickness 
is  5/32  in.  A  3/16  in.  electrode  may  be  used,  especially  between 
flue  sheet  and  middle  sheet,  owing  to  the  greater  thickness  of  the 
.flue  sheet.  The  heat  value  should  always  be  as  great  as  is  con- 
sistent with  good  welding. 

If  "thermic  syphons,"  shown  by  Fig.  88,  are  to  be  applied  to- 
gether with  a  new  firebox,  the  seams  connecting  the  syphon  to  the 
crown  sheet  should  be  welded  with  the  box  on  its  side,  which  will 
place  the  long  seams  of  the  syphon  in  a  horizontal  position.  These 
seams  should  be  reinforced  on  both  the  water  and  fire  sides.  The 
diaphragm  plates,  shown  in  Fig.  89,  may  be  welded  to  the  flue 
sheet  with  the  firebox  in  either  position,  since  the  location  of  the 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       179 

joints  to  be  welded  eliminates  overhead  welding  in  either  case. 
These  seams  should  also  be  welded  in  sections,  as  previously 
described. 

The  object  of  beveling  the  edges  of  all  seams  from  the  fire  side 
is  that  in  the  event  of  making  any  repairs  along  the  line  of  weld, 
which  of  necessity  must  be  done  from  the  fire  side  in  most  cases, 
it  would  not  be  necessary  to  make  such  large  openings  to  remove 


FIG.  87 — Joint  of   Crown    Sheet  Welded  with   Electric  Arc.     Photograph 
Taken  Looking  up  from  Drop  Pit 

the  old  welded-in  metal.  Extreme  openings  must  be  avoided,  as 
it  has  been  demonstrated  in  service  that  such  welds  cannot  be 
depended  upon.  This  is  due  no  doubt  to  the  fact  that  if  the  weld 
is  not  reinforced  the  cast  metal  applied  in  the  large  opening  pos- 
sesses less  strength  than  the  original  plate  and  will  break  when 
slightly  distorted.  If  on  the  other  hand  a  wide  section  of  this 
kind  is  built  up  in  an  effort  to  stiffen  the  line  of  weld,  the  greater 
thickness  will  result  in  a  greater  temperature  at  that  point,  which 


180 


ELECTRIC  ARC   WELDING 


may  result  in  local  strains  that  cause  rupture.  No  more  of  the 
original  metal  should  ever  be  removed  than  is  necessary  to  pro- 
vide access  to  insure  fusion  all  along-  the  entire  edges  to  be  joined 


FIG.  88 — Two-Syphon   Application  to  a  Medium  Width  Firebox  with  a 
Combustion  Chamber 


and  the  width  of  the  reinforcement  should  not  be  much  more 
than  the  opening  between  the  beveled  edges  at  the  widest  point 


FIG.  89 — The  Diaphragm  Plate  Welded  in  by  Means  of  Electric  Arc 

for  sections  of  this  thickness.  Proper  and  improper  reinforce- 
ment is  shown  in  Fig.  90.  Arc  welds  do  not  tend  to  break  along 
the  line  of  union  when  properly  made;  the  weakest  point  is 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       181 


through  the  cast  metal;  for  this  reason  the  center  of  the  weld 
should  have  the  greatest  thickness. 

The  door  hole  flange  seam  may  be  butt  welded,  using  the  back 
step  method  or  it  may  be  lap  welded,  as  shown  by  Fig.  91.  Both 
methods  are  used  and  both  are  in  successful  operation. 

The  objection  raised  by  some  to  the  lap  weld  is  that  scale  will 
form  between  the  unwelded  edges  on  the  water  side  and  produce 


Proper  Reinforcement 


y'  Improper  Reinforcement 


FIG.  90 — Proper  and  Improper  Reinforcement 


a  prying  effect.  However,  no  such  trouble  has  developed  so  far 
as  can  be  learned  from  those  using  the  lap  type  joint  at  the  door 
hole  flange  seam.  A  lap  welded  joint  for  the  door  hole  flange 
seam  is  less  difficult  to  make  than  is  the  butt  weld  joint  and  if  it  is 
as  good,  it  is  preferable.  A  view  showing  an  arc  welded  seam 
across  the  outside  door  sheet  is  illustrated  in  Fig.  92. 


,Weld 


Weld 

I 

I    .__ 


Butt  Weld.  Lap  Weld. 

FIG.  91 — Two  Types  of  Door  Hole  Flange  Welds 

Mud  Ring. — It  is  the  practice  to  weld  the  edges  of  the  sheet 
to  the  mud  ring  to  prevent  leaks  from  developing,  as  shown  by 
Fig.  93.  The  edges  of  the  sheet  should  first  be  beveled  and  in 
order  securely  to  join  the  sheet  to  the  ring  a  space  on  the  ring,  at 
least  equal  to  the  thickness  of  the  sheet,  should  be  cleaned  with  a 
roughing  tool.  The  usual  practice  is  to  extend  the  weld  approxi- 
mately 12  in.  from  the  corner  each  way.  In  the  case  of  riveted 
lap  seams  in  the  firebox  the  weld  is  also  extended  along  the  edges 


182 


ELECTRIC  ARC   WELDING 


of  the  flange  seams  above  the  grate  frame.    A  5/32  in.  electrode 
is  appropriate  for  this  work. 

Many  mud  ring  corners  of  the  above-mentioned  type  have 
failed,  due  to  the  fact  that  the  sheet  extended  down  so  near  the 
bottom  edge  of  the  mud  ring  that  only  a  very  light  weld  could  be 
made,  and  as  the  mud  rings  are  usually  hammered  iron,  having 
laminated  characteristics,  the  corners  tear  off.  This  feature  must 
be  given  additional  consideration  in  boiler  construction  if  the  best 
results  are  to  be  obtained  from  welding  the  edges  of  the  sheets 


FIG.  92 — Arc  Welded  Seam  across  Outside  Door  Sheet 

to  the  mud  ring.  The  edge  of  the  sheet  should  not  extend  nearer 
than  J4  in.  to  the  bottom  edge  of  the  mud  ring.  At  present  it  is 
difficult  to  obtain  ]/\  in. 

Welding  Tubes  to  the  Tube  Sheet. — The  welding  of  tubes 
to  the  flue  sheet  is  not  as  simple  an  operation  as  it  may  at  first 
seem.  Every  conceivable  method  of  flue  setting  has  been  tried ; 
many  methods  had  little  or  no  commercial  value.  For  example, 
flue  sheet  holes  have  been  countersunk  to  provide  an  opening  for 
the  added  metal,  and  the  flues  set  flush  with  the  fire  side  of  flue 
sheet,  as  shown  in  Fig.  94.  In  other  cases  the  flues  were  simply 
set  and  rolled,  allowing  the  flue  to  extend  beyond  the  flue  sheet  a 
slight  distance  to  permit  a  fillet  weld,  as  shown  by  Fig.  95.  This 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       183 


practice  is  still  in  effect  to  some  extent  in  some  parts  of  the  coun- 
try, especially  with  the  large  flues.  Among  the  most  important 
factors  that  determine  the  performance  of  flues  is,  of  course,  the 


'~  Mud  Ring 
FIG.  93 — Welding  the  Edges  of  the  Sheet  to  the  Mud  Ring 

water  conditions  and  with  welded  flues,  as  with  unwelded  flues, 
the  water  conditions  will  determine  to  some  extent  the  method  of 
application. 

In  general,  the  best  and  safest  practice  is  to  use  the  welding 


FIGS.  94  and  95 — Two  Types  of  Flue  Welding 

FIG.  95— Fillet  Weld  Flue  Extended 


FIG.  94— Flue  Sheet  Hole  Counter- 
sunk with   Flue   Set  Flush 


process  to  seal  the  joint  between  the  flue  and  the  flue  sheet  and 
not  depend  entirely  upon  the  weld  to  anchor  the  flue  to  the  sheet, 
as  the  relatively  small  amount  of  cast  metal  will  not  alone  with- 
stand the  severe  strains  imposed  upon  the  flue  joint,  especially 


184  ELECTRIC  ARC   WELDING 

when  water  conditions  are  bad.  The  surface  of  the  flue  sheet 
should  be  as  smooth  as  possible  in  order  to  reduce  the  tendency  of 
honey-combing.  This  is  especially  necessary  with  fireboxes  not 
equipped  with  brick  arches. 

The  practice  that  is  considered  best  for  preparing  and  welding 
locomotive  boiler  tubes  at  the  present  time  is  as  follows : 

(7)  The  flue  sheet  around  the  edges  of  the  flue  hole  should  be 
perfectly  clean.  This  may  be  accomplished  with  sandblast,  rough- 
ing tool,  or  with  a  wire  brush  if  the  scale  is  not  too  bad. 

(2)  Copper  ferrules  placed  in  the  flue  sheet  holes  should  be 
set  1/16  in.  back  from  the  edge  of  the  fire  side  of  the  flue  sheet. 


Electric 

Weld 


Copper 
Ferrule 

FIG.  96— Method  of  Procedure  in  Welding  Beaded  and  Expanded  Flues 

(5)  Soap  water  should  be  used  as  a  substitute  for  oil  as  a  lubri- 
cant for  the  expander.  Oil  must  not  be  present. 

(4)  When  the  flues  are  applied  they  should  extend  through  the 
sheet  approximately  J4  in- ;  they  should  then  be  rolled  and  flared, 
after  which  they  should  be  expanded  with  a  Prosser  expander 
and  finished  as  though  they  were  not  to  be  welded,  after  which 
the  sheet  around  the  flue  heads  should  be  cleaned  by  sandblasting 
— or  if  not  too  dirty  they  may  be  cleaned  with  a  wire  brush  and 
then  be  welded  in  the  following  manner : 

Start  the  welding  at  the  bottom  of  the  flue  at  point  A  as  shown 
in  Fig.  96  and  weld  in  an  upward  direction,  A-O-B ;  then  return 
to  point  A  and  weld  in  an  upward  direction,  A-X-C,  lapping  over 
the  end  of  the  first  bead  approximately  */>  in.  This  will  avoid  the 
possibility  of  pin  holes  where  the  arc  was  broken  at  the  finishing 
point  of  first  bead.  The  deposited  metal  should  not  project 
farther  than  flush  with  the  flue  bead. 

For  2  in.  flues  a  y&  in.  electrode  is  generally  used,  with  a  heat 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       185 

value  slightly  above  the  normal  value  used  for  this  size  electrode. 
For  5  in.  flues  a  5/32  in.  electrode  should  be  used,  with  as  much 
heat  as  is  consistent  with  good  welding.  In  both  cases  the  heat 
value  must  be  sufficient  properly  to  fuse  or  perpetrate  the  heavy 
flue  sheet,  which  will,  of  course,  tend  to  fuse  away  the  compara- 
tively thin  tube  bead  unless  proper  care  is  exercised.  To  avoid 
the  burning  of  the  bead  the  major  pQrtion  of  the  arc  flame  should 
be  directed  against  the  flue  sheet,  or  the  arc  flame  should  be  played 
upon  the  flue  sheet  more  than  upon  the  flue  bead. 

As  the  thin  edge  of  the  flue  bead  is  fused  through  by  the  arc,  if 
the  surface  around  the  edges  of  the  flue  hole  is  scaly,  or  otherwise 
dirty,  an  excessive  heat  or  undue  manipulation  of  the  arc  will  be 
required  to  slag  off  scale  or  dirt  and  secure  fusion  between  the 
,flue  bead  and  the  sheet  This  will  make  a  smooth  weld  difficult 
and  will  tend  to  cause  burned  metal  in  the  weld. 

If  the  copper  ferrule  extends  out  under  the  flue  bead  when  the 
welding  begins,  the  arc  will  be  erratic,  owing  to  the  difference  in 
the  conductivity  of  the  two  metals  from  which  the  arc  is  estab- 
lished. This  will  also  make  a  smooth,  sound  weld  practically  im- 
possible. If  oil  is  present  the  oil  and  the  soot  formed  by  the  burnt 
oil  will  interrupt  the  arc  and  the  flow  of  the  metal.  It  has  been 
found  that  hardness  is  increased  with  the  presence  of  oil. 

The  flues  should  be  applied  the  same  as  though  they  were  not 
to  be  welded,  for  the  reason  previously  explained ;  i.  e.,  to  assist 
the  weld  in  anchoring  the  flue  and  to  make  a  smoother  finished 
job.  The  copper  ferrule  may  be  omitted  if  the  water  conditions 
are  exceptionally  good.  If  the  water  conditions  do  not  permit  the 
boiler  to  be  kept  clean  and  free  from  scale  the  temperature  of  the 
surfaces  exposed  to  the  fire  will,  of  course,  be  increased.  For 
this  reason  it  is  evident  that  the  copper  gasket  or  ferrule  setting 
will  help  overcome  the  excessive  distortion  due  to  the  increased 
temperature. 

If  a  welded  flue  should  develop  a  leak  the  old  weld  of  the  leaky 
flue  should  be  entirely  removed  and  the  flue  thoroughly  worked 
with  expander  and  beading  tool  and  then  welded.  This  can  be 
done  best  if  the  original  flue  setting  is  made  with  the  copper 
ferrule. 

It  is  the  practice  of  some  roads  to  have  the  locomotive  fired  up 


186  ELECTRIC  ARC   WELDING 

or  to  make  a  trial  trip  before  welding  the  flues ;  this  is  beneficial 
if  oil  is  used  in  applying  the  flues.  If  such  has  been  the  case  the 
oil  will  be  burned  off,  this  permitting  a  better  weld  to  be  made. 
The  theory  has  been  advanced  that  the  boiler  should  be  allowed 
to  make  a  trip  or  be  fired  up  in  order  to  permit  the  flues  to  take 
a  setting  under  heat  conditions,  but  this  is  not  considered  neces- 
sary when  the  flues  are  applied  and  welded  as  has  been  outlined. 
From  the  foregoing  it  is  apparent  that  the  welding  of  flues  is  an 
additional  expense  to  be  added  to  the  cost  of  installing  flues ;  how- 
ever, this  added  first  cost  is  many  times  offset  by  the  decreased 
operating  expense. 

The  following  data  serve  to  indicate  the  present  speed  and  cost 
of  welding  tubes  and  flues,  although  it  has  been  demonstrated  that 
it  is  possible  to  weld  double  the  number  of  flues  per  hour. 

COST  OF  WELDING  SMALL  TUBES 

Per  Tube 

Average  cost  per  tube,  at  the  rate  of  15  per  hour, 
figuring  labor  at  77  cents  per  hour,  and  welding 
iron  and  power  at  25  cents  per  hour $  .068 

Cost  of  Welding  Large  Flues 

Per  Flue 

Average  cost  per  tube,  at  the  rate  of  3  per  hour, 
figuring  labor  at  77  cents  per  hour,  and  welding 

iron  and  power  at  25  cents  per  hour 0.34 

Cost  of  welding  tubes  in  one  engine  of  229  tubes 

at  6.8  cents  per  flue 15.57 

Cost  of  welding  tubes  and  flues  in  one  engine  of 
190  small  tubes  at  6.8  cents  per  tube,  and  30 
large  flues  at  34  cents  per  flue 23.12 

The  cost  of  the  welding  iron  and  power  is  based  on  the  average 
price  of  iron  and  upon  the  power  consumption  of  a  modern  weld- 
ing equipment  and  the  average  cost  per  kilowatt-hour  for  power. 

On  a  central  western  railroad,  where  welding  of  tubes  and 
flues  to  the  tube  sheet  is  standard  practice,  according  to  the  gen- 
eral boiler  inspector  the  performance  is  as  follows : 

The  running  repairs  on  flues  and  tubes  on  engines  with  welded 
flues  has  been  reduced  to  almost  nothing.  More  than  50  per  cent 
of  the  locomotives  that  had  flues  welded  a  year  or  more  ago  are 
returning  to  the  shops  after  running  50,000  to  90,000  miles  with- 
out ever  having^any  work  done  on  the  flues.  The  condition  of  the 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       187 

flues  on  their  arrival  at  the  shops  was  such  that  only  the  lower 
flues,  where  the  scale  is  heavy,  were  renewed.  The  upper  small 
flues  on  saturated*  and  superheated  steam  engines,  and  usually 


FIG.  97— Showing  Beaded  and   Expanded  Flues  Welded  by  Electric  Arc 

all  of  the  superheated  flues  on  practically  all  of  the  superheated 
engines,  ran  two  shoppings  without  leaking  before  they  were 
changed.  It  is  evident,  therefore,  that  the  additional  expense  of 


FIG.  98 — Sections  of  Beaded  and  Expanded  Flues  Welded  by  Electric  Arc; 
One  with  and  One  without  Copper  Ferrule 

welding  the  flues  is  many  times  offset,   especially  when  water 
conditions  are  bad. 

The  tendency  to  honey-combing  is  m>  greater  with  welded  flues 
than  when  they  are  not  welded.  Scale  and  dirt  may  be  more 
noticeable  with  welded  flues,  but  this  is  usually  due  to  the  less 


188 


189 


190  ELECTRIC  ARC   WELDING 

frequent  working  and  hammering  on  the  flue  sheet.  For  the  same 
reason  slightly  more  scale  may  form  on  the  water  side,  of  the  flue 
sheet.  It  is,  however,  certainly  less  work  and  expense  to  clean  off 
the  flue  sheet  occasionally  than  to  expand  the  flues  every  few  trips 
and  calk  them  possibly  every  trip. 

The  life  of  a  flue  sheet  is  greater  where  the  flues  are  welded 
and  the  liability  of  cracks  is  less,  since  the  destructive  effects  pro- 
duced by  the  frequent  rolling  and  working  of  the  flues  are  prac- 
tically eliminated.  Views  of  beaded  and  expanded  arc  welded 
flues  are  shown  in  Figs.  97  and  98.  In  the  photographic  repro- 


FIG.   101 — Patch  on  Flue  Sheet  and  around  Arch  Tube  Welded  with 

Electric  Arc 

duction,  Fig.  98,  sections  of  two  welded  flues  are  shown  one  with 
and  one  without  copper  ferrule. 

Boiler  Repairs. — The  manner  in  which  some  of  the  different 
parts  of  the  firebox  are  cut  out  when  it  becomes  necessary  for 
them  to  be  renewed,  is  shown  in  Figs.  99  and  100.  Views  of 
repaired  flue  sheets  are  shown  in  Figs.  101  and  102.  When  sheets 
or  patches  are  cut  out,  care  should  be  exercised  to  select  locations 
that  will  afford  good  foundations  for  the  weld.  Cutting  through 
stay-bolt  holes,  arch  tube  holes  and  old  welds  should  be  avoided. 

The  surfaces  of  all  beveled  edges  must  be  finished  by  chipping. 
This  is  necessary  to  secure  a  uniform  line  and  opening  between 
the  edges  to  be  welded  and  to  insure  clean  surfaces  on  which  to 
weld.  All  foreign  substances  must  be  removed  to  prevent  slag 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       191 

inclusions,  which  if  present  will  greatly  impair  the  strength  of  the 
joint. 

The  bottom  edges  of  all  horizontal  seams  will  not  require  as 
much  bevel"  as  other  edges ;  a  20-deg.  angle  will  be  sufficient.  All 
other  edges,  i.  e.,  the  top  edges  of  horizontal  seams  and  both 
edges  gf  vertical  or  flat  seams  should  be  beveled  to  a  30-deg. 
angle.  An  opening  of  approximately  y%  in.  between  beveled  edges 
has  become  standard  for  firebox  plate. 


FIG.  102 — Front  Flue  Sheet  Joints  Welded  with  Electric  Arc 

There  are  two  conditions  in  boiler  work  under  which  welding 
must  be  done ;  one  is  rigid  welding,  and  as  its  name  indicates,  the 
parts  oppose  free  play.  The  other  condition  is  the  opposite.  The 
former  condition,  however,  predominates  in  boiler  work.  Rigid 
welding  is  not  so  difficult  if  properly  done,  as  explained  in  another 
chapter  under  the  headings  "Expansion  and  Contraction  of  Parts 
Welded"  and  "Contraction  of  Fused  Metal." 

The  back  step  method  of  welding  has  been  adopted  for  practi- 
cally all  seams.  The  method  avoids  considerable  distortion  of  the 
sheets  and  possible  concentration  of  contraction  strains  at  one 
point  which  so  often  causes  rupture.  This  method  eliminates 
much  of  the  expensive  corrugating  of  sheets,  etc.,  which  is  prac- 


192 


ELECTRIC  ARC   WELDING 


ticed  by  a  number  of  roads.  The  only  provisions  for  expansion 
and  contraction  considered  necessary  with  the  "back  step"  method 
are  to  give  a  slight  roll  to  sheets  and  to  slightly  dish  patches. 

Side  sheets  should  be  set  and  bolted  in  place—  stay-bolts 
screwed  in  from  the  wrapper  sheet  may  be  used  to  push  the  sheet 
in  one  direction  and  bolts  to  draw  in  in  the  opposite  direction, 
thus  aligning  the  edges.  Stay-bolts  may  then  be  applied  every 
fourth  or  fifth  hole  in  the  row  adjacent  to  the  line  of  weld. 

The  electrode  material  most  commonly  used  in  firebox  welding 
is  mild  steel  or  ingot  iron  in  the  Y%  in.,  5/32  in.  and  3/16  in.  sizes 


Vertical  Seam. 


FIG.  103 — Method  of  Procedure  in  Welding  Side  Sheets 

• — of  these  sizes  the  5/32  in.  is  the  most  extensively  used.  The  % 
in.  is  often  used  when  the  edges  are  very  thin  or  when  the  opening 
between  the  edges  is  small.  The  3/16  in.  is  sometimes  used  for 
the  first  layer  to  fill  the  opening  approximately  flush  with  one  run, 
afterwards  applying  the  finishing  layer  with  a  5/32  in.  or  %  in. 
electrode. 

The  heat  value  should  always  be  as  great  as  can  be  used  without 
burning  the  added  metal  or  overheating  the  sheet  adjacent  to  the 
weld.  With  the  proper  heat  the  sheet  will  develop  a  dark  red  heat 
a  distance  of  ^4  m-  around  the  point  where  the  arc  is  drawn, 
shortly  after  the  welding  is  started. 

It  is  the  usual  practice  to  allow  slightly  more  opening  at  the  top 
seam  which  is  welded  first,  than  the  bottom  seam,  to  allow  for  the 
slight  drawing.  If  the  opening  is  greater  at  one  end  than  at  the 


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194 


ELECTRIC  ARC   WELDING 


other,  the  welding  should  progress  toward  the  end  having  the 
greatest  opening. 

The  seams  of  side  sheets  should  be  welded  in  the  order  shown 
in  sketch,  Fig.  103.  Front  or  back  flue  sheets  when  cut  out  as 
shown  in  Fig.  100,  should  be  welded  by  laying  the  seams  off  in 


Weld  from  Fire  Side  and  finish  Flush  on 
Wafer  Side.      Use  fhe  same  method  as 
described  for  other  seams. 


FIG.  105— A  Crown  Patch  Weld 

three  or  four  sections  and  welding  in  the  order  shown  in  Fig.  104. 
If  seams  are  welded  from  an  overhead  position  the  metal  de- 
posited between  the  beveled  edges  will  sag  slightly,  leaving  a  con- 
cave type  of  weld  on  the  side  opposite  that  from  which  the  weld- 
ing is  done.  It  is  for  this  reason  that  crown  seams  should  be  gone 


6-f-arf  the  Wefd  in  fhe 
cenfer  at  fhe  fop 
and  Weld  either  way 


Edge  of  Sheet  We/cfed 
fo  Mud  Rfng 


FIG.  106 — Welding  Corner  Patches 

over  on  the  water  side  to  secure  a  flush  joint  and  not  necessarily 
to  reinforce  the  joint.  , 

Side  sheet  patches  should  have  a  slight  dish.  The  weld  should 
be  executed  in  the  same  general  way  as  that  for  side  sheets  or 
flue  sheets.  The  method  used  for  welding  crown  patches  is 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       195 

shown  by  Fig.  105.     The  method  used  for  welding  corner  patches 
is  shown  in  Fig.  106. 

When  cracks  develop  in  the  knuckle  of  the  back  flue  sheet  they 
should  be  welded  from  the  water  side  if  possible  and  slightly  rein- 
forced on  the  fire  side.  The  weld  should  be  made  in  compara- 


Weld  in  numerical 'order  and  in 
the  direction  shown  by  arrows 


FIG.  107— Procedure  in  Welding  a  Crack  which  Developed  in  Knuckle  of 

Back  Flue  Sheet 

tively  short  sections  as  shown  in  Fig.  107,  finishing  each  section 
before  starting  another.  This  holds  true  for  practically  all  frac- 
ture welding  in  fireboxes  or  elsewhere  if  the  parts  are  rigid. 

Fractures  extending  from  one  rivet  hole  to  another  between  the 
mud  ring  rivets  are  welded  as  shown  by  Fig.   108.     Fractures 


Start  the  Weld  in  the  center  of  the  fracture 
and  Weld  Fir^f  to  one  Rivet  Hofe  and  then 
the  other,  Welding  over  and  around  Rivet- 
Head. 

FIG.  108 — Repairing  Fractures  between  Rivet  Holes  at  Mud  Ring 

above  the  mud  ring  that  extend  from  one  rivet  hole  to  another  or 
arch  tube  hole  cracks  should  be  repaired  by  applying  a  patch.  It 
is  possible  to  weld  stay-bolt  hole  cracks  by  applying  a  round  disc 
as  shown  in  Fig.  109.  It  has  been  found  difficult  to  make  a  weld 
hold  in  this  location  when  made  without  the  disc.  One  disc  is 
used  for  each  hole  through  which  the  fracture  extends. 


196 


ELECTRIC  ARC   WELDING 


Vertical  flue  sheet  knuckle  cracks  are  welded  from  the  water 
side,  starting  in  the  center  of  the  crack  and  finishing  first  one  half 
and  then  the  other.  Fractures  in  this  location  should  be  repaired 
in  this  manner  only  in  an  emergency.  A  new  top  portion  or  a 
new  sheet  should  be  applied  instead  when  conditions  permit. 
When  cracks  develop  in  the  door  hole  radius  a  new  collar  should 
be  applied  as  shown  by  Fig.  110.  In  an  emergency,  cracks  are 
welded  by  beveling  the  edges  and  welding  from  the  center  to  one 
end  of  the  fracture,  returning  to  the  center  and  welding  toward 
the*  opposite  end  of  the  fracture.  If  two  or  more  cracks  are 


"T 


Section  A-A  Welded.  "   Details  of  Disc.         Section  A~A. 

FIG.  109 — Repairing  Fractures  by  Means  of  a  Disc 

present,  each  crack  should  be  completed  before  cutting  out  and 
welding  another. 

Corroded  or  oversize  wash-out  plug  holes  are  repaired  as  shown 
by  Figs.  Ill,  112  and  113.  The  washer  shown  in  Fig.  Ill  is  cut 
in  half  to  permit  it  to  go  through  the  hole  and  be  placed  on  the 
water  side  to  serve  as  a  backing  for  the  deposited  metal.  This 
same  method  is  often  used  to  fill  in  stay-bolt  holes  that  have  be- 
come checked  around  the  edges.  The  sleeve  or  round  disc  pro- 
vides a  better  metal  than  the  cast  filled-in  metal  in  which  to  tap 
new  threads. 

Old  riveted  seams  that  become  defective  are  repaired  by  remov- 
ing the  rivets  or  patch  bolts  and  cutting  a  bevel  on  the  edges 
exposed  to  the  fire.  The  old  rivet  holes  are  plug  welded  after 
which  the  beveled  edge  is  lap  welded  to  the  adjoining  sheet  as 
shown  by  Fig.  114. 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       197 

Mud  ring  corners  are  best  welded  by  cutting  out  a  portion  of 
the  sheet  on  the  fire  side  to  permit  access  for  beveling  the  frac- 
tured edges  of  the  mud  ring  so  that  the  welding  may  be  done  from 
the  top  side  of  the  mud  ring,  afterwards  fitting  a  new  patch  in 
place  and  welding. 

A  new  patented  flexible  stay-bolt  has  been  placed  on  the  market, 
the  application  of  which  utilizes  arc  welding.  One  of  the  as- 
semblies is  shown  by  Fig.  115. 

The  arc  welding  process  is  used  extensively  for  welding  calk- 
ing edges  on  old  riveted  seams.  One  example  of  this  is  in  weld- 


FIG.  no 

5/de  Sheet 

'        '•  'NN 


Door  Ho/e  F/ange 
We/a  m  nurmerrcal 'order and 
in  the  direction  as  shown  by 
arrows. 


FIG.  in  FIG.  112  FIG.  113 


FIG.  us 


FIG.  no — Procedure  in  Applying  New  Door  Hole  Collar 

FIG.  n  i  to  1 13 — Methods   of   Repairing   Corroded   or  Over-Size  Washout 

Plugs 

FIG.  114 — Repairing  an  Old  Riveted  Seam 
FIG.  115— The  Sleeve  of  a  Flexible  Staybolt  Welded  to  Sheet 


ing  the  calking  edge  of  riveted  joints  in  the  smokebox  of  loco- 
motives, when  rivets  become  loose  and  effect  the  vacuum  which 
is  required  for  draft  through  the  firebox.  There  are  many  other 
applications  in  the  construction  and  repairing  of  locomotive  boil- 
ers for  the  arc  welding  process  of  which  no  mention  has  been 
made.  The  examples  cited,  however,  will  serve  to  indicate  the 
progress  that  has  been  made  in  this  field. 

Welding  in  Ship  Yards  and  Other  Industries. — The  weld- 
ing of  piping,  plates  and  shapes  for  ships,  cars,  and  building 
structures  is  similar  to  that  of  locomotive  boiler  welding,  as  the 
materials  ordinarily  used  are  about  the  same  considered  from  an 


198  ELECTRIC  ARC   WELDING 

arc  welding  standpoint.  Tentative  regulations  for  the  application 
of  arc  welding  to  ship  construction  have  been  issued  by  Lloyds, 
which  signifies  merited  recognition  of  the  art  as  a  safe  means  for 
many  purposes  in  ship  construction. 

During  the  war  the  interest  created  by  the  possibilities  of 
the  application  of  arc  welding  resulted  in  the  formation  of  a 
welding  committee,  known  as  the  Welding  Committee  of  the 
Emergency  Fleet  Corporation.  At  the  conclusion  of  the  war 
the  committee  was  discontinued  by  The  Emergency  Fleet  Cor- 
poration. However,  in  order  to  continue  the  research  started  by 
it,  the  American  Welding  Society  was  organized,  which  is  com- 
posed largely  of  the  same  personnel  as  the  original  committee. 
Branches  of  this  society  are  being  organized  in  all  the  principal 
cities  of  the  country.  It  is  hoped  that  the  society  will  eventually 
be  the  recognized  body  to  serve  as  a  guide  in  the  art  of  welding. 

The  regulations  by  Lloyds  for  ship  welding  allow  either  butt 
joints,  with  sufficient  butt  straps,  or  lap  joints.  Up  to  the  issu- 
ance of  these  regulations  welding  in  shipyards  was  generally 
limited  to  attachments  that  were  not  structural  parts  of  the  ship, 
such  as  deck  collars,  joints  for  continuous  railing  rods,  stairs, 
bulkhead  partitions,  grab  rods,  deck  houses,  reinforcing  and  re- 
pairing broken  castings,  angle  smith  work,  forming  different  parts 
by  angle  plates,  etc.,  low  pressure  tank  seams,  pipe  joints  and 
similar  work.  Pressure  vessels  and  structural  parts  of  the  ship 
could  not  be  welded  unless  submitted  for  consideration. 

Some  small  vessels,  barges  and  sections  of  barges  have  been 
constructed  by  arc  welding.  The  Chester  Ship  Building  Company 
constructed  a  60-foot  mid-ship  section  in  the  welding  of  a  1,200- 
ton  bulk  barge,  designed  for  service  in  Mexico.  The  shell  and 
deck  plates  were  %  in.  and  the  transverse  framing  members,  in- 
tercostals,  and  the  like,  were  all  of  5/16  in.  plate.  The  results 
were  very  satisfactory  and  the  tight  joints  were  made  without 
punching  a  hole  and  for  approximately  one-fourth  the  cost  of 
time  and  material  required  by  other  methods.  There  have  been 
many  other  similar  cases  of  experimental  ship  construction  in- 
volving extensive  arc  welding,  all  of  which  have  been  given 
publicity  in  some  of  the  various  business  papers  and  technical 
journals. 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       199 

Examples  of  welding  applications  in  the  United  States  Navy 
Yards  are  shown  in  Fig.  116,  corners  for  hatch  hole  covers,  and 
Fig.  117,  a  spray  shield  for  a  gun.  The  nature  and  kind  of  ma- 
terials to  which  welding  is  applied  in  marine  work  is  similar  in 
many  respects  to  that  encountered  on  railroads ;  so  that  the 


FIG.   116 — Hatch  Cover   Corners  Welded  in  the  Navy  Yard 

methods  which  have  been  described  in  detail  would  in  most  cases 
be  applicable  to  other  structural  engineering. 

A  study  of  the  factors  which  govern  the  methods  of  applica- 
tion, such  as  composition  of  metals,  thermal  capacity,  arrange- 
ments, position  of  work,  service  requirements,  etc.,  will  be  re- 
quired in  each  case  before  the  exact  method  can  be  determined. 
Different  methods,  types  of  joints,  and  weld  designs  will  be 
required  depending  upon  conditions,  so  that  any  examples  of 


200  ELECTRIC  ARC   WELDING 

application  that  may  be  given  would  only  serve  to  suggest  meth- 
ods for  like,  or  similar  cases. 

A  bottom  rudder  brace  for  a  small  lake  ship,  which  had  been 
completely  broken  and  was  repaired  by  arc  welding  is  shown  in 
Fig.  118.  It  will  be  noted  that  the  reinforcing  was  made  by  weld- 
ing on  round  rods ;  this  is  similar  to  the  method  employed  for 
reinforcing  locomotive  frames. 

Arc  Welding  in  Building  Construction. — An  example  which 
marks  the  beginning  of  the  application  of  arc  welding  to  building 
construction  is  to  be  found  in  the  case  of  a  building  erected  by  the 


FIG.   117 — Spray  Shield  for  a  Gun  Constructed  by  Electric  Welding 

Electric  Welding  Company  of  America  at  Brooklyn,  N.  Y.,  for 
its  own  use. 

Before  proceeding  with  the  work  of  erecting  the  building  en- 
tirely by  arc  welding,  it  was  necessary  to  obtain  permission  from 
the  various  city  building  departments,  and  such  permission  could 
only  be  given  if  certain  tests  were  made  which  would  satisfy  the 
building  officials  that  a  welded  structure  would  be  absolutely  safe 
and  would  compare  favorably  in  other  respects  v/ith  a  riveted 
steel  framework. 

Certain  samples  of  welded  joints  were  requested  for  the  tests. 
The  samples  submitted  and  the  test  results  were  as  follows : 

First  sample,  1%  in.  by  ^  in.  lap  welded  bars,  lapped  1^4  m- 
and  welded  across  the  edges;  when  subjected  to  a  direct  tension 
of  60,000  Ib.  per  sq.  in.  a  break  occurred  in  the  bar  3  in.  from  the 
weld.  Examination  at  the  line  of  union  between  the  added  and 
parent  metal  showed  no  distinct  boundary  between  them. 


RAILROAD  AND  STRUCTURAL  APPLICATIONS      201 

Second  sample.  This  sample  consisted  of  two  angles  (2  in.  by 
3  in.  by  $i  in.)  set  at  right  angles  and  welded  at  the  intersection. 
This  sample  was  set  in  a  machine  so  that  there  was  a  horizontal 
lever  arm  of  8  in.  from  the  center  of  pressure  to  the  center  of 
weld  and  intersection,  and  developed  a  beam  load  of  11,375  Ib.  at 


FIG.    118 — Rudder    for    a   Lake    Boat    which    Was    Repaired   by    Electric 

Welding 

the  weld,  or  a  torsional  stress  of  91,000  Ib.  at  the  weld,  with  no 
apparent  distress  to  the  weld. 

The  tests  of  these  samples  were  entirely  satisfactory  to  the 
building  officials.  Permission  was  subsequently  given  to  proceed 
with  the  erection  of  the  steel  framework,  but  there  was  still  an- 


202 


ELECTRIC  ARC   WELDING 


other  test  to  be  made  of  the  steel  trusses  of  40  ft.  span,  which 
were  to  be  used  to  sustain  the  roof.  These  trusses  were  of  fan 
type  of  design  and  all  members  were  electrically  welded  together, 
no  bolts  or  rivets  being  used.  The  trusses  were  spaced  20  ft. 
apart,  supported  by  8  in.  x  8  in.  H-beam  columns  19  ft.  high ;  on 
the  sides  of  these  columns  brackets  were  fastened  to  carry  an 
overhead  traveling  crane  of  five-ton  capacity.  The  weight  of  each 


FIG.    119 — Bracket   Constructed   and  Joined   to   Column   by   Metallic   Arc 

Welding 

truss  was  about  1,400  Ib. ;  the  top  and  bottom  chords  were  com- 
posed of  4  in.  x  5  in.  x  ^  in.  tee  irons ;  the  struts  were  3  in.  x  2  in. 
x  2^ -in.  angles;  the  purlins  were  10-in.,  15-lb.  channels. 

The  trusses  were  designed  for  a  live  load  of  40-lb.  per  sq.  ft., 
each  truss  supporting  a  panel  of  800  sq.  ft.  They  were  tested  at 
a  load  of  120  Ib.  to  the  square  foot,  or  a  total  load  of  48  tons  on 
the  two  trusses.  The  load  consisted  of  gravel  in  bags  which 
were  piled  in  tiers  on  planking  arranged  for  the  purpose. 

Readings  were  taken  at  different  increments  of  the  loadings  for 
the  deflection  in  the  truss  or  members. 


RAILROAD  AND  STRUCTURAL  APPLICATIONS      203 

The  trusses  were  left  under  load  48  hours  and  a  reading  taken 
showed — East  support  settled  15/16  in.,  West  support  24  in. 
actual;  point  No.  2,  7/16  in.  actual;  point  No.  4,  y2  in.  actual  de- 
flection; point  No.  3,  9/16  in.  actual  deflection.  Two  days  after- 
ward the  load  was  entirely  removed  and  readings  taken  at  this 
time  showed  all  points  in  the  trusses  had  returned  to  their  original 
positions,  leaving  no  permanent  deflection  except  at  point  No.  3, 
where  there  was  a  deflection  of  1/16  in. 


FIG.  120 — Peak  of  Truss  Showing  Members  Joined  by  Electric  Arc  Welding 

To  quote  from  the  official  report :  "From  the  above  it  is  evident 
that  electric  welding  is  a  dependable  method  of  uniting  structural 
members  and  is  stiffer  than  riveting  if  the  work  is  properly  per- 
formed. 

The  test  was  witnessed  by  members  of  all  'the  building  depart- 
ments in  Greater  New  York,  and  as  a  result  a  permit  was  issued 
for  the  erection  of  the  first  building  of  its  kind. 

The  time,  labor  and  material  saved  through  the  elimination  of 
the  fabrication  necessary  for  riveting  obviously  constitutes  an 
item  in  favor  of  the  arc  welded  joint;  and  actual  test  on  a  com- 
mercial scale  will  demonstrate  that  structural  work  by  electric 
arc  welding  can  be  done  at  a  lower  cost  than  by  riveting.  As  the 
use  of  proper  materials,  methods  of  application  and  competent 


204 


ELECTRIC  ARC   WELDING 


operators  become  more  general,  the  extension  of  the  process  to 
almost  all  phases  of  structural  engineering  will  be  inevitable. 

Figs.  119  to  121  show  some  of  the  joints  embodied  in  the  build- 
ing structure. 


FIG.  121 — Members  of  Roof  Frame  Joined  by  Electric  Arc  Welding 

Welding  Locomotive  Frame  Members  and  Similar  Parts. — 
Broken  locomotive  frame  members  have  been  repaired  success- 
fully by  the  arc  welding  process  when  the  proper  methods  were 
used  and  when  reasonable  care  was  exercised  by  the  operator. 


RAILROAD  AND  STRUCTURAL  APPLICATIONS      205 


According  to  the  location  of  the  fracture  and  the  position  of  the 
members,  the  edges  to  be  joined  should  preferably  be  beveled  as 
shown  in  Fig.  122.  Where  the  oxy-acetylene  cutting  torch  is  used 
to  bevel  the  edges,  the  film  of  blue  oxide  left  on  the  surface  by 
the  cutting  process  must  be  removed  with  a  chisel,  roughing  tool 
or  sand  blast ;  otherwise,  when  the  welding  is  started,  the  arc  will 


ChSlightly  overdiam.of  Electrode  used. 


Tack  Welded,  Reinforcing  Rod- 


Complete  Weld  of  Reinforcing 
Rod  to  Frame 


l7     ^  Not  less  than 

than  I  "wide. 
Weld  Complete 


t       J.' 

Section 
A-A. 


FIG.   122 — Method   of   Welding   Horizontal   Locomotive   Frame   Member, 
Double  "V,"   Side  Position 

be  erratic,  which  will  result  in  poor  penetration  and  undue  oxida- 
tion of  the  added  metal.  In  addition  to  the  cleaning  of  the  sur- 
faces to  be  joined,  the  scale  which  forms  on  top  of  the  added 
metal  must  always  be  removed  before  adding  another  layer.  Slag 
inclusions  are  a  common  source  of  weakness  in  welds,  and  can  be 
eliminated  only  by  keeping  the  work  perfectly  clean  as  the  weld- 
ing progresses.  The  electrode  material  commonly  used  is  mild 
steel,  3/16  in.  in  diameter.  Electrodes  of  %  in.  diameter  may  be 
used  if  the  capacity  of  the  equipment  will  permit. 


206 


ELECTRIC  ARC   WELDING 


To  compensate  for  the  contraction  of  the  added  metal,  prior  to 
starting  the  welding  the  abutting  members  should  be  expanded  or 
forced  apart  from  J/£  in.  to  3/16  in.,  depending  on  size  of  frame, 
heat,  and  method  of  welding  employed.  The  free  space  between 
frame  points  should  be  greatest  at  that  end  of  the  opening  toward 
which  the  welding  progresses ;  the  points  should  not  be  separated 
evenly  as  in  the  case,  for  example,  of  the  thermit  process  where 
the  contraction  of  the  molten  mass  occurs  practically  simultane- 
ously. A  jack  or  wedge  may  be  used  to  force  the  members  apart. 

When  the  point  at  which  the  welding  was  started  cools  the 
jacks  or  wedges  may  be  removed;  on  heavy  members  this  can 

-H 


-5  or  5  Firebox  Steel 


FIG.   123— Filling  Pieces   for  Five  and   Six-Inch  Frames 

sometimes  be  done  before  the  weld  is  completed.  When  the  open- 
ing is  filled  entirely  by  metal  added  from  the  electrode,  the  weld 
is  made  in  vertical  layers,  starting  at  the  center  of  the  section  and 
welding  alternately  first  on  one  side  and  then  the  other.  This 
method  is  preferable  to  that  of  applying  the  metal  in  horizontal 
layers,  as  in  the  former  case  there  is  less  likelihood  of  the  in- 
effective long  arc  welding.  To  eliminate  the  necessity  of  filling 
all  this  opening  with  metal  that  has  passed  through  the  arc,  filling 
pieces  as  shown  by  Fig.  123  may  be  used,  providing  the  operator 
is  of  the  conscientious  type  and  will  take  particular  care  to  secure 
fusion  between  the  edges  of  the  plates  and  frame  scarf.  The  space 
between  the  edges  of  the  filling  piece  and  the  beveled  edges  of  the 
frame  should  not  be  less  than  %  in. 

In  executing  welds  such  as  shown  in  Figs.  124  to  129  inclusive, 
the  edges  of  the  flush  plate  should  first  be  welded  to  the  bottom 
of  the  frame.  A  bead  of  metal  should  then  be  deposited  in  the 
corner  formed  between  the  top  side  of  the  flush  plate  and  the 


RAILROAD  AND  STRUCTURAL  APPLICATIONS      207 

bottom  beveled  edge  of  the  frame.  With  a  filler  piece  in  place,  the 
plug  weld  should  next  be  made,  then  the  edges  welded  to  the 
frame,  finishing  the  welds  flush  with  the  top  of  the  piece  in  order 
that  the  next  piece  will  lie  close  to  the  preceding  one.  Addi- 
tional pieces  should  be  welded  in  place  in  the  same  manner,  weld- 


I27_Longitudinal  Section 


FIG.   124-Frame  Fracture 


FIG.    125  —  Frame    Prepared,    Flush 


Plate     and     One     Filling     Piece     FIG.   128—  Vertical  Section 
Welded  in  Place  A-B 


FIG.  126— Finished  Weld 


FIG.  129 — Longitudinal  Section 
Showing  Reinforcing  All  on  One 
Side  in  Case  of  Close  Clearance 


FIG.  124  to  129 — Showing  Method  when  Work  Can  Be  Done  from  Both 
Sides  of  the  Frame 


ing  three  or  four  pieces  first  on  one  side  and  then  on  the  other. 
Vertical  members  are  welded,  as  shown  by  Fig.  130.  When 
conditions  permit  all  heavy  sections  of  this  nature  should  be 
prepared  and  welded  from  both  sides,  and  should  be  reinforced 
50  per  cent  to  75  per  cent  when  the  nature  of  the  service  is  severe, 
as  is  usually  the  case.  When  conditions  do  not  permit  welding 
to  be  done  from  both  sides,  such  members  may  be  prepared  and 


208 


ELECTRIC  ARC   WELDING 


Not  less 

0*  Slightly  over  di'am.        than^j 
of  Electrode. 


Clearance  for 
Shoe  or  Mfedge 


c  .. 

Reinforcing  Rod  not  less  than  /g  thick 
or  more  than   I"  wide 


FIG.    130 — Method   of    Welding    Vertical    Member    of    Frame    Pedestal — 
Double  V,  Side  Position 

welded  from  one  side,  in  which  case  the  work  may  be  done  in  the 
same  general  way,  as  described  for  the  double  "V"  weld. 

When  the  work  cannot  be  done  from  either  side,  the  methods 
shown  in  Figs.  131  to  135  may  be  used.  The  edges  of  the  flush 
plate,  also  the  reinforcing  plate,  if  access  permits  its  use — should 
first  be  welded  to  the  frame.  The  beveled  edges  should  then  be 

•Fracture 


FIG.  131 
'£  org  Reinforcing  Plate 


FIG.  134 — Longitudinal  Section  C-D 


Not  Less  Than 


FIG.  132 — Frame  Prepared,  Flush 
Plate  and  Reinforcing  Plate  Tack 
Welded  in  Place 


- 

Reinforcing      > 


Strips 


.__*. 


FIG.   133— Finished  Weld 


FIG.  135 — Vertical  Section  A-B 


FIG.  131  to  135 — Showing  Procedure  when  Work  Cannot  Be  Done  from 
Either  Side  of  the  Frame 


RAILROAD  AND  STRUCTURAL  APPLICATIONS      209 

joined  by  welding  metal  in  the  opening  until  the  weld  is  flush  with 
the  opposing  members.  The  reinforcing  can  then  be  made  by 
welding  on  strips,  as  shown  in  the  illustrations.  In  place  of  the 
plate  strips  for  reinforcing,  J^  in.  or  ^  in.  rods  may  be  used  if 
desired.  Plates  wider  than  1  in.  should  not  be  used  unless  the 
surface  next  to  the  frame  can  be  welded  thereto.  Plates  wider 
than  1  in.  may  be  used  if  provisions  are  made  for  plug  welds. 
For  frame  members  the  strips  or  rods  are  less  expensive  to  pre- 
pare and  are  to  be  preferred. 


FIG.   136 — A  Completed  Weld  Using  Filler  Plates  in  Locomotive  Frame 

Extreme  care  must  be  exercised  to  obtain  a  perfect  union  be- 
tween the  added  metal  and  the  beveled  edges  of  the  frame  mem- 
bers, also  between  the  added  metal  and  the  edges  of  the  filling 
pieces.  The  use  of  the  filler  plates  effects  a  very  large  saving  in 
time,  and  the  quality  of  the  weld  has  proven  to  be  just  as  good 
as  welds  made  without  the  plates,  if  the  proper  care  is  exercised. 
The  plates  have  had  mechanical  treatment,  which  makes  them 
superior  to  metal  that  would  ordinarily  be  added  by  the  arc.  If 
the  plates  are  carried  in  stock  in  two  or  three  standard  sizes  and 
the  frames  are  cut  out  to  accommodate  the  plates,  the  largest 
frame  can  be  welded  with  the  arc  welding  process  in  approxi- 
mately the  same  time  as  that  required  for  other  processes.  For 
small  frames  less  time  may  be  required. 


210  ELECTRIC  ARC   WELDING 

The  cost  of  performing  the  weld  itself  has  always  been  in  favor 
of  the  electric  arc  process,  being  on  an  average  of  50  per  cent  less 
than  that  with  other  methods.  The  only  question  which  has  been 
raised  is  that  of  locomotive  delay  in  the  case  of  large  frames ;  this 
can  be  offset  by  the  use  of  the  filler  plates.  A  finished  weld  made 
with  filler  plates  is  shown  in  Fig.  136. 

Welding  Driving  Wheels  Tires,  Rolled  Steel  Wheels,  and 
Steel  Tired  Wheels. — The  arc  welding  process  is  extensively 
used  for  building  up  worn  flanges  and  flat  spots  on  driving  wheel 
tires,  rolled  steel  wheels  and  steel  tired  wheels.  A  typical  example 
of  the  composition  of  steel  tires  is  shown  in  the  following  table : 

Manganese,  between    50  per  cent  and  .80  per  cent 

Phosphorus,  not  over   05  per  cent 

Sulphur,  not  over 05  per  cent 

Silicon,    not   over 35  per  cent 

Carbon  (Class  1),  not  less  than. .  .50  per  cent  or  over  .70  per  cent 
Carbon  (Class  2),  not  less  than..  .60  per  cent  or  over  .80  per  cent 
Carbon  (Class  3),  not  less  than. .  .70  per  cent  or  over  .85  per  cent 
Class  1. — Driving  tires  for  passenger  engines. 
Class  2. — Driving   tires    for    freight    engines   and   tires    for   trailer 

wheels. 
Class  3. — Driving  tires   for  switch   engines. 

Offhand  it  would  not  seem  legitimate  to  apply  the  welding 
process  to  a  driving  flange .  for  fear  of  the  effects  of  localized 
heat,  which  in  most  cases  certainly  cannot  be  ignored.  The  fact 
that  the  practice  has  been  so  extensive,  without  any  particular 
regard  for  the  effects  of  the  heat,  and  that  comparatively  few 
failures  have  resulted,  seems  to  indicate  that  many  parts  (even 
those  high  in  carbon)  under  certain  conditions,  with  prescribed 
methods  and  limitations,  can  be  safely  welded. 

The  method  which  is  considered  best  for  building  up  flanges  is 
shown  in  Fig.  137.  In  this  case  the  added  metal  or  beads  extend 
around  the  periphery  of  the  tire;  the  metal  is  added  in  sections 
8  in.  to  12  in.  long.  One  section  at  a  time  is  finished  before  start- 
ing another.  The  metal  can  be  applied  by  this  method  more 
smoothly  and  with  less  effort  than  if  the  arc  is  operated  back  and 
forth  across  the  flange.  The  main  object  in  the  method  described 
is  to  keep  the  arc  moving,  thus  preventing  the  flange  from  heating 
to  any  appreciable  depth.  This,  together  with  the  extreme 
localization  of  the  arc's  heat,  and  the  radiating  ability  of  the  mas- 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       211 

sive  part,  will  confine  the  structure  disturbance  close  to  the  sur- 
face, usually  to  a  depth  of  about  Y%  in.,  leaving  the  main  body  of 
the  flange  or  tire  structure  undisturbed. 

No  trouble  has  been  experienced  with  tires  welded  in  this  man- 
ner. This  probably  is  due  to  the  fact  that  the  tire  is  not  subjected 
to  alternate  stresses.  It  is  believed  by  those  who  have  analyzed 
this  method,  its  effects  and  the  nature  of  the  service,  that  the  most 
that  could  happen  would  be  for  the  added  metal  to  shell  out.  Flat 
spots  are  built  up  in  the  same  general  way — i.  e.,  in  such  a  manner 
as  to  keep  the  tire  practically  cool. 

A  small  electrode  J/6  in.  or  5/32  in.  in  diameter  should  be  used 
with  a  heat  value  as  low  as  consistent  with  fusion.  The  composi- 


FIG.  137 — Building  up  Flanges  of  Wheels  by  Arc  Welding  Process 

tion  of  the  electrode  should  approximate  that  of  the  tire.  How- 
ever, such  electrodes  cannot  be  used  to  advantage  unless  .the  ma- 
terial is  treated  "coated,"  so  that  the  constituent  parts  of  the 
electrode  will  not  be  lost  in  passing  through  the  arc.  This  feature 
is  important  and  necessary  if  the  best  economy  is  to  be  realized 
from  the  work.  At  present  practically  all  of  this  class  of  work 
is  being  done  with  the  ordinary  mild  steel.  Even  with  this  ma- 
terial much  economy  is  effected. 

Reclamation  of  Axles. — The  nature  of  the  service  demanded 
of  axles  requires  prescribed  methods  and  certain  limitations  if 
the  welding  process  is  to  be  applied  to  them.  Axles,  unlike 
flanges,  are  subject  to  alternate  stresses,  and  therefore  cannot  be 
welded  except  at  the  collar,  unless  the  effects  of  the  localized  heat 
are  afterwards  removed  by  annealing.  The  practice  on  one  of  the 
western  roads  is  as  follows :  For  reclaiming  axles,  the  standard 
sizes  and  limiting  dimensions  of  M.  C.  B.  axles  for  passenger, 


212 


ELECTRIC  ARC   WELDING 


freight  and  tender  trucks,  as  shown  in  Fig.  138,  should  be  fol- 
lowed.   The  figures  enclosed  in  circles  indicate  the  limit  of  wear. 

Axles  condemned  for  lateral  wear  occurring  at  the  collar  and 
shoulder  of  the  journal  can  in  most  cases  be  returned  to  service 
if  only  the  collar  is  built  up  and  turned  to  the  standard  dimensions. 


Length  Orera//  76 


M.C.B. 


Length  Orera/f  72g 
M.C.B.  * 


^          Length  Overall   7'o$   ~T) 


FIG.    138— Working    Standards    for    Reclaiming    Axles    by    Electric    Arc 

Welding 


Where  this  is  the  case,  it  shall  be  done  and  preheating  or  anneal- 
ing will  not  be  required.  Welding  between  wheel  seats  is  not  per- 
missible. The  welding  process  may  be  used  to  build  up  worn 
shoulders,  or  wear  caused  by  dust  guard,  etc.  If  facilities  are 
available  for  annealing  after  welding,  the  annealing  should  be 
done  by  heating  to  a  temperature  of  1,450  deg.  to  1,500  deg.  Fahr., 
which  is  equal  to  a  bright  red  color;  the  axles  should  be  cooled  in 


FIG.  139 — Fracture  Prepared  for  Electric  Welding 


FIG.  140 — Electric  Welded  Coupler 


213 


214 


ELECTRIC  ARC   WELDING 


the  open  air  free  from  draft,  care  being  taken  not  to  lay  on  damp 
ground  or  cold  massive  parts  such  as  would  tend  to  chill  the  axle 
and  thus  produce  local  strains. 


FIG.  141— A  Triple  Weld  in  Face  of  Coupler 

Reclaiming  Car  Couplers,  Knuckles,  Etc. — On  at  least  one 
large  railroad  a  vast  number  of  car  couplers  are  being  success- 
fully reclaimed.  The  work  includes  not  only  minor  repairs  such 
as  building  up  worn  shanks,  but  also  the  welding  of  broken  eyes, 
coupler  heads  and  shanks.  The  latter  class  of  work  is  only  per- 


FIG.  142— An  Electric  Welded  Shank 

formed  by  first-class  operators.  Treated  electrode  material  is 
used,  i.  e.,  the  electrode  is  coated  with  a  material  designed  to 
envelope  the  arc  stream  and  exclude  the  atmosphere  and  limit  the 
formation  of  oxides  and  nitrides  as  well  as  to  prolong  the  cooling 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       215 

of  the  added  metal,  thus  securing  a  more  ductile  metal  than  that 
obtained  from  the  ordinary  bare  electrode. 

In  this  class  of  work  fractures  are  cut  out  in  the  usual  way.  A 
prepared  piece  of  work  is  illustrated  in  Fig.  139.  Fractures 
which  have  been  welded  and  which  were  of  considerable  length 
are  shown  in  the  coupler  head,  Fig.  140.  This  weld  was  made  in 
two  sections  by  starting  in  the  center  and  welding  to  one  end, 
then  starting  the  second  section  at  the  opposite  end  and  finishing 
at  the  center,  each  section  being  completed  before  starting  another. 


FIG.   143 — Built-up   Coupler  Shank 

A  triple  weld  in  the  face  of  a  coupler  head  is  shown  in  Fig.  141, 
and  Fig.  142  shows  a  weld  extending  half  way  around  the  shank. 

These  examples  represent  some  of  the  most  severe  conditions. 
In  most  cases  there  is  only  one  fracture  in  the  coupler  body,  the 
majority  being  located  in  the  face  of  the  coupler  head.  A  worn 
coupler  shank  built  up  to  original  size  by  welding  on  a  piece  of 
steel  plate  is  shown  in  Fig.  143. 

Fractured  and  worn  knuckles  are  repaired  or  built  up  in  the 
same  general  way  as  couplers.  The  cost  of  making  such  welds  is 
approximately  10  per  cent  of  the  cost  of  new  couplers  or  knuckles. 

A  method  of  converting  the  old  6^  in.  coupler  butts  to  the  new 
9%  in-  standard  is  shown  in  Fig.  144.  This  is  accomplished  by 
applying  cast  steel  shims  to  increase  the  dimensions  from  6^2  in. 


j 

- 

. 

T 

4 

^r  i 

1  i 

3 





— 

— 

216 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       217 

to  9^  in.    One  railroad  recently  converted  8,000  couplers  in  this 
manner.    The  enormous  saving  effected  thereby  is  apparent. 
Metallic  Arc  Welding  of   Car   Bolsters. — A   fractured   car 


FIG.   145 — Fractured  Car  Bolster    Prepared   for   Electric  Welding 

bolster  which  has  been  cut  out  and  prepared  for  welding  is  shown 
in  Fig.  145.  The  fractures  are  welded  in  the  same  manner  as  ex- 
plained for  couplers.  In  addition,  reinforcing  plates  are  applied. 


FIG.    146 — Welded    Fracture    (See   Fig.    145) 

The  welded  fracture  is  shown  in  Fig.  146,  and  in  Figs.  147  and 
148  is  shown  the  manner  of  applying  the  reinforcing  plates. 
When  fractured  bolsters  are  received  which  have  previously 


FIG.   147 — How  Reinforcing  Plates  Are  Applied 

been  repaired  by  riveting  on  straps,  these  straps  and  rivets  are 
removed  and  the  fracture  is  welded.  The  rivet  holes  are  then 
welded  up  and  a  reinforcing  plate  is  welded  on.  The  reinforcing 


218  ELECTRIC  ARC   WELDING 

is  extended  over  the  zone  within  which  the  particular  class  of 
bolster  has  indicated  a  weakness. 

Welding  of  cast  steel  side  truck  frames  can  be  done  success- 
fully by  the  use  of  electrode  material  of  such  a  grade  as  to  give  a 
reasonable  degree  of  ductility  in  the  weld,  and  by  the  proper 
applications.  As  a  rule  the  fractures  encountered  in  parts  of  this 
character  are  located  in  the  tension  members,  as  shown  at  A,  Fig. 


FIG.  148 — How  Reinforcing  Plates  Are  Applied 

149.  In  order  to  secure  a  factor  of  safety  at  the  joint  a  reinforc- 
ing plate  should  be  applied  to  the  underside  of  the  tension  mem- 
ber and  the  fracture  edges  beveled  and  welded  from  the  opposite 
side,  as  shown.  The  examples  shown  are  similar  to  many  other 
parts  and  no  doubt  the  same  methods  would  be  applicable. 

Most  steel  castings  that  develop  fractures  were  weak  or  defec- 
tive to  begin  with.  A  close  inspection  of  a  number  of  such  parts 
will  prove  this  conclusively.  Among  the  most  common  defects 
are :  air  holes,  sand  pockets  and  shrinkage  cracks.  If  in  repairing 


RAILROAD  AND  STRUCTURAL  APPLICATIONS      219 


such  castings  these  defects  are  removed,  the  castings  will  in  many 
cases  be  better  than  they  were  originally. 

All  cast  steel  car  castings  or  similar  parts  should  be  annealed 
after  welding  by  heating  to  a  temperature  of  about  1500  deg.  F. 
to  1550  deg.  F.  and  keeping  them  at  this  temperature  for  not  less 
than  two  hours.  This  will  not  only  remove  any  bad  effects  caused 
by  the  welding  heat,  but  will  also  restore  the  normal  structure  in 


Bettendorf  Side  Frame;  Fracture  at  "A"  or  "B"  and  Worn  Wheel  Hub  Face  at"G". 


Bevelallcdg 
one  side  to  30° 


Weld  Prepared, Fracture 

at"A"or'B". 


'C"=  Wheel  Hub  Face  to  be  built  up  if 
worn  by  Lateral  Motion. 

0= Slightly  Over  Diam.  of  Electrode  used. 
YY=Approx.  5"or  over  when  Sandholes  are  bad. 
T-Not  less  than  '/z  of  "x". 
P=  Plate  extended  across  bottom  of 
frame  and  welded  on  all  4  edges. 


Weld  Finished. 


Sec/Hon  A-A. 


FIG.   149 — Repairing  a   Cast   Steel    Side   Truck  Frame  by   Metallic  Arc 

Welding 

case  the  part  has  become  fatigued,  due  to  prolonged  service. 
With  the  proper  equipment  and  welding  materials,  the  success  of 
this  class  of  welding  depends  upon  rigid  adherence  to  proper 
methods  of  application  and  subsequent  annealing.  On  one  rail- 
road where  this  practice  has  been  going  on  for  over  a  year,  prac- 
tically no  failures  have  resulted.  In  fact,  it  is  almost  common 
practice  in  many  parts  of  the  country  to  use  the  arc  welding 
process  to  repair  and  reinforce  castings  and  parts  to  add  sufficient 


220  ELECTRIC  ARC   WELDING 

strength  to  enable  them  to  withstand  the  service.  Through  work 
of  this  character  the  process  has  acquired  the  name  of  the  "put- 
ting on"  tool  in  some  shops. 

Some  of  the  parts  on  which  practical  applications  of  this  nature 
bave  been  made  are:  drawbar  castings  on  Vanderbilt  type  of 
.tenders  for  Mikado  (2-8-2)  locomotives,  draft  sill  end  castings  on 
refrigerator  cars,  locomotive  frames  where  new  and  larger  cylin- 
ders have  been  applied,  crossheads,  etc. 

Space  limitations  prohibit  the  mention  of  the  many  applications 
of  the  arc  welding  process  to  machinery  parts  on  railroads.  How- 
ever, some  idea  as  to  the  extent  of  its  application  is  given  in  the 
list  of  parts  welded  which  was  taken  from  the  records  covering  a 
period  of  60  days  at  a  division  point  on  one  road  which  has  three 
portable  metallic  arc  welding  equipments  for  locomotive  use. 
During  this  period  a  large  number  of  parts  of  railroad  equipment 
were  repaired,  as  is  evident  from  the  list,  which  is  included  here 
because  the  question  has  been  quite  frequently  asked,  what  parts 
of  railroad  equipment  are  electric  welded? 

LIST  OF  PARTS  ELECTRIC  WELDED  AND  CLASS  OF  WORK  PERFORMED 

Firebox 

Fire  door,  fracture  welded 
Fire  door,  patches  welded  on 
Front  flue  sheet,  fracture  welded 
Sheets  welded  to  mud  ring  corners 
Side  sheets,  fracture  welded 
Side  sheets,  patches  welded  in 
Side  sheets  welded  in 

Boiler 

Flue  sheets,  fracture  welded 
Flues  welded  to  flue  sheet 
Superheater  pipe  built  up 

Frames  and  Attachments 

Belly  braces  welded  to  frame 
Binders  built  up 
Binders,  liners  welded  to 
Binders,  wedge  bolt  hole  plugged 
Buckle  sheet,  holes  plugged 
Buckle  studs  welded  to  boiler 
Bumper  castings  built  up 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       221 

Cab  brackets 

Deck  casting  fracture  welded 
Equalizer  fulcrum  arms,  fracture  welded 
Frames  built  up 
Frames,    fracture    welded 
Frame  braces,  holes  plugged  up 
Frame  braces  welded  to  frame 
Frame  jaws  built  up 
Frame  splices,  holes  plugged  up 
Front  end  casting,  fracture  welded 
Guide  blocks  built  up 
Guide  yoke  built  up 
Guide  yoke,  fracture  welded 
Guide  yoke  bracket,  fracture  welded 
Smoke  arch  brace,  fracture  welded 
Tail  pieces  built  up 

Cylinders 

Cylinder,  fracture  welded 

Front  cylinder  head,  fracture  welded 

Running  Gear  Parts 

Crank  pins,  collars  welded  to  crank  pins 

Driving  boxes  built  up 

Driving  boxes,  fracture  welded 

Driving  box,  shoes  and  wedges ;  broken  flanges  welded 

Engine    truck   pin   built    up 

Hub   pin   built   up 

Tires,  spots  built  up 

Tires,  shims  welded  to  tires 

Trailer  boxes,   lugs  welded  on  boxes 

Trailer  tires  built  up 

Trailer  tires,  fracture  welded 

Trailer  tires,  spot  welded  to  wheel  center 

Trailer  yoke 

Truck,    fracture   welded 

Truck  bolsters  built  up 

Truck  frames,  welded  to  center  piece 

Truck  side  frames,  fracture  welded 

Wheel  spokes,  fracture  welded 

Connecting  Rods 
Main  rod  built  up 
Main  rod  straps  built  up 
Rod  straps  built  up 
Rod  straps,  strips  welded  to 
Side  rods  reinforced 


222  ELECTRIC  ARC   WELDING 

Side  rods,  collar-welded  on  side  rods 

Side  rods,  lateral  plates  welded  on  side  rods 

Crosshcads  and  Piston   Rods 
Crosshead  built  up 
Crosshead,  fracture  welded 
Crosshead,  gibs  welded  on 
Crosshead,  holes  plugged 
Crosshead,  liner  welded  to 
Crosshead  pin  built  up 
Crosshead  pin  holes  built  up 
Crosshead,  strips  welded  on 
Piston  collar  built  up 
Piston  rod  built  up 

Valve   Gear 
Blade  pins  built  up 
Combination  lever,   fracture  welded 
Eccentric  arms  built  up 
Eccentric  keys  built  up 
Link,  holes  plugged 
Link  blocks  built  up 
Link  hanger  built  up 
Link  pins  built  up 
Link  saddles  built  up 
Motion  pins  built  up 
Motion  plates,  fracture  welded 
Rocker  arms  built  up 
Rocker  arms,  fracture  welded 
Tumbling  shaft  arm,  fracture  welded 
Valve  yoke  built  up 
Valve  yoke  lugs  built  up 

Valve  yoke,  stem  built  up 

• 

Steam  and  Exhaust  Pipes 
Dry  pipes,   fracture   welded 
Exhaust  pipes,  fracture  welded 
Nozzle  stands  built  up 
Nozzle  stands,  holes  plugged 

Brake  and  Spring  Rigging 
Brake  hanger,  posts  built  up 
Brake  hangers  built  up 
Brake  hangers  welded  to  frames 
Equalizer  fulcrum  pin  built  up 
Equalizer  jaws  built  up 
Equalizer  stands  built  up 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       223 

Spring  equalizer  bushing  welded 
Spring  saddles  built  up 
Trailer  spring  guides  built  up 
Truck  equalizer  built  up 

Tender 

Axle   collar   built   up 
Side  bearings  built  up 
Tank,  fracture  welded 
Tank  goose  neck 
Truck  bolster,  fracture  welded 

Not  Classified 

Air  pump  piston  built  up 

Bell  cranks,  fracture  welded 

Bushings  spot  welded 

Chafing  iron  built  up 

Chafing  iron,  steel  plate  welded  in 

Draw  bar  yokes  built  up 

Drill  press  shafts  built  up 

Dynamo  doors,  fracture  welded 

Gasoline  engine  cylinder,  fracture  welded 

Grease  cups  welded  to  rods 

Link  latch   blocks  built  up 

Motor  car  castings,  fracture  welded 

Reverse  lever,  fracture  welded 

Reverse  lever  latch  built  up 

Running  board  brackets,  extensions  welded  on 

Throttle  latch  built  up 

The  American  Railroad  Association  committee  on  welding 
truck  side  frames,  bolsters  and  arch  bars  has  recommended  that 
welding  of  cracks  or  fractures  should  not  be  permitted  on  axles, 
arch  bars,  car  wheels  or  tires,  truck  equalizers,  spring  or  bolster 
hangers,  brake  wheels,  coupler  bodies  or  knuckles,  knuckle  pin, 
locks,  lifters  or  on  parts  made  of  alloy  steel  or  heat-treated  carbon 
steel.  It  is  not  surprising  that  these  recommendations  were  made 
if  the  conclusion  was  based  on  the  average  results  obtained  on 
railroads  throughout  the  country  as  was  no  doubt  the  case. 

It  is  generally  conceded  that  there  is  an  extremely  wide  varia- 
tion in  the  quality  of  welds,  the  strength  ranging  from  almost 
nothing  to  values  equal  to  that  of  the  welded  part.  Considering 
the  results  that  have  been  obtained  with  the  small  amount  of  atten- 
tion that  has  been  given  to  the  factors  which  determine  the  quality 


224 


ELECTRIC  ARC   WELDING 


of  welds,  such  as  the  training  of  operators,  quality  and  kind  of 
material  that  goes  into  the  weld,  and  methods  employed  in  per- 
forming the  weld,  etc.,  it  would  seem  that  any  limitations  that 


FIG.   150 — Fractured   Cast   Iron   Cylinder   of   a    Mikado   Type  Locomotive 
Prepared    for   Arc   Welding 

are  placed  on  autogenous  welding  should  be  designed  to  encourage 
the  development  of  the  art.  With  no  other  process  is  so  much  ex- 
pected from  the  efforts  expended  as  from  autogenous  welding. 
Without  any  special  guidance  or  training  welding  operators  on 


RAILROAD  AND  STRUCTURAL  APPLICATIONS 


225 


railroads  are  almost  daily  required  to  perform  welds  under  prac- 
tically impossible  conditions,  and  from  the  results  of  these  hap- 


FIG.   151 — Welded  Cast   Iron   Cylinder   of   Mikado   Type   Locomotive 

hazard  applications  the  value  of   the  process   is  judged  by   the 
executives. 

The  repairing  of  broken  or  fractured  cast  iron  cylinders  are 


226 


ELECTRIC  ARC   WELDING 


among  some  of  the  applications  which  have  been  condemned  by 
many,  and  while  all  cast  iron  parts  cannot  as  yet  be  advantageous- 
ly welded  many  parts  can.  A  very  bad  break  in  a  cylinder  of 


FIG.  152 — Journal  Box  Completely  Built  up    (Foreign  Railroad) 

a  Mikado  type  locomotive  prepared  for  metallic  arc  welding  is 
shown  in  Fig.  150.  The  fracture  is  lined  with  ]/2  in.  wrought 
iron  studs  spaced  approximately  2^/2  in.  apart.  The  weld  was 


FIG.   153 — Gear  Casing   Built  up    (Foreign   Railroad) 

made  in  sections  by  the  back  step  method,  progressing  in  an  up- 
ward direction.  The  completed  weld  is  shown  in  Fig.  151.  No 
preheating  or  annealing  was  employed ;  instead,  the  heat  was  kept 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       227 


m 

JSm 


FIG.  154— Wheels  Cast  in  Separate  Parts  Are  Assembled  by  Arc  Welding 
Process   (See  Fig.  155) 

as  low  as  consistent  with  good  welding  by  using  a  small  y§  in. 
diameter  mild  steel  electrode.  In  the  past  most  welds  of  this 
kind  were  made  with  a  bare  electrode.  It  is  now  considered  that 
better  work  can  be  done  with  a  "coated"  electrode,  in  which  case 
the  metal  flows  smoothly  and  secures  a  better  union  with  the  cast 
iron.  The  cylinder  referred  to  above  has  been  in  constant  service 


FIG.  155— Wheels  Cast  in  Separate  Parts  Are  Assembled  by  Arc  Welding 
Process  (See  Fig.  154) 


228 


ELECTRIC  ARC   WELDING 


since  April,  1919.  Many  other  welds  of  its  kind  have  been  in 
service  without  any  trouble  being  experienced  for  two  years  or 
more. 

It  may  be  of  interest  to  know  how  some  of  the  other  countries 


FIG.  156 — Truck  Frame  and  Bolster  Built  up  by  Arc  Welding    (Foreign 

Railroad) 


are  progressing  in  the  electric  welding  art.     A  few  illustrations 
will  give  some  indication. 

.A  journal  box  completely  built  up  by  the  arc  process  is  shown 
in  Fig.  152. 


FIG;  157— Truck  Frame  and  Bolster  Built  up  by  Arc  Welding   (Foreign 

Railroad) 


RAILROAD  AND  STRUCTURAL  APPLICATIONS       229 

A  gear  casing  of  an  electrically  driven  car,  completely  built  up, 
is  shown  in  Fig.  153. 

Gear  wheels,  which  are  cast  in  separate  parts,  as  shown  in  Fig. 
154,  are  then  assembled  by  arc  welding,  as  shown  in  Fig.  155. 

A  truck  frame  and  bolster  built  by  arc  welding  is  shown  in 
Figs.  156  and  157. 

This  work  was  done  by  the  New  South  Wales  Government 
tramways  at  Sydney,  Australia,  which  recently  had  a  representa- 
tive traveling  through  America,  gathering  information  for  the 
purpose  of  further  extending  the  process  of  arc  welding. 


XI 

MISCELLANEOUS   NOTES  AND  ARC  WELDING 

DATA 

In  most  all  engineering  practice  it  is  necessary  to  know, 
with  a  fair  degree  of  certainty,  what  may  be  expected  of  a  ma- 
terial intended  for  any  given  purpose,  especially  in  cases  where 
human  life  may  be  jeopardized  in  case  of  a  failure  in  service. 
For  this  reason  the  subjects  of  greatest  interest  to  the  user  of  arc 
welding  are  first  the  physical  properties  of  a  weld,  and  second  the 
alterations  of  the  physical  properties  of  the  part  affected  by  the 
welding  process. 

In  a  weld  made  by  the  metallic  arc  process  the  metal  to  be 
added  usually  consists  of  mild  steel  or  ingot  iron  which  has  been 
rolled  or  drawn  into  rod  or  wire  form.  In  the  process  of 
welding,  the  rod  or  wire  is  melted  and  deposited  to  other  metal, 
also  melted,  the  mass  then  cooling  into  a  cast  form  in  which  the 
artificial  structure  produced  by  the  rolling  or  drawing  of  the  wire 
is  entirely  changed.  A  weld,  therefore,  is  but  a  casting  and  will 
never  have  all  the  properties  to  the  same  degree  as  a  similar  piece 
which  has  had  mechanical  treatment. 

The  physical  properties  of  the  added  metal  will  depend  almost 
entirely  upon  the  following  factors :  Composition,  impurities, 
slag  inclusions,  gas  holes  and  crystal  structures. 

In  the  making  of  steel,  such  elements  as  carbon  manganese, 
vanadium,  nickel,  chromium,  tungsten,  molybdenum,  and  the  like, 
are  intentionally  added  in  varying  proportions  to  impart  different 
properties  depending  on  the  service  requirements. 

Composition. — In  bare  electrode  metallic  arc  welding  the 
metal  is  subjected  to  very  high  temperatures,  some  of  it  actually 
passing  into  the  form  of  vapor;  the  iron  constituent  melts  at  a 
higher  temperature  than  the  other  elements  ordinarily  present,  ex- 
cept carbon,  which  combines  readily  with  the  oxygen  of  the  air 
and  forms  carbon  monoxide  or  carbon  dioxide  gas.  Most  of  the 

230 


MISCELLANEOUS  NOTES  AND  DATA  231 

elements  present  in  an  electrode  are  lost  in  vapor  or  oxide  in 
traversing  an  arc  exposed  to  the  air.  For,  this  reason,  practically 
all  bare  wire  welding  has  been  done  with  a  mild  steel  or  ingot  iron 
electrode  material.  Where  a  mild  steel  material  is  used  the 
carbon  and  manganese  are  reduced  to  exceedingly  low  values. 
A  typical  analysis  of  a  deposit  from  a  mild  steel  electrode  of  0.15 
to  0.20  carbon  and  0.50  to  0.60  manganese  will  be  0.05  carbon  and 
not  over  0.20  manganese.  The  other  elements,  such  as  phos- 
phorus, sulphur  and  silicon,  being  low  to  begin  with  do  not  ap- 
pear to  be  greatly  affected. 

The  metal  obtained  in  the  weld  with  the  bare  electrodes  ordi- 
narily used  is,  therefore,  a  form  of  cast  metal  exceedingly  low 
in  carbon  and  manganese  and  other  such  elements  as  are  usually 
added  to  metal  to  impart  certain  desirable  characteristics. 

Impurities. — The  physical  quality  of  welds  seems  to  hinge 
upon  the  impurities  more  than  any  other  factor,  since  the  degree 
of  ductility  is  largely  dependent  upon  these  impurities.  The  con- 
ditions under  which  welding  is  done,  i.e.,  exposed  to  the  air,  sub- 
jects the  metal  to  the  effects  of  the  oxygen  and  nitrogen.  The 
characteristic  brittleness  by  which  all  autogenous  welds  are  more 
or  less  marked  was  for  some  time  thought  to  be  due  entirely  to 
oxidation,  because,  no  doubt,  under  ordinary  conditions  of 
fusion,  nitrogen  has  but  little  effect  on  iron.  According  to  the 
scattered  facts  the  authors  have  been  able  to  collect  on  this  subject 
it  is  now  commonly  agreed  among  the  metallurgists  who  have 
conducted  research  along  this  line  that  the  oxygen  content  will  not 
alone  account  for  the  lack  of  ductility.  Nitrogen,  as  low  as  0.06 
per  cent,  is  sufficient  to  reduce  the  elongation  on  low  carbon  steel 
as  much  as  80  per  cent.  It  is  obviously  one  of  the  most  effective 
elements  for  making  steel  brittle.  Under  the  temperature  and 
conditions  of  the  welding  arc,  the  nitrogen  becomes  very  effective, 
resulting  in  the  weld  becoming  nitroized.  Strauss  found  0.12  per 
cent  nitrogen  in  an  electric  weld.  Another  metallurgist  found 
that  a  weld  made  with  a  bare  electrode  contained  forty  times  as 
much  nitrogen  as  that  of  the  plate  material.  The  usual  amount 
of  nitrogen  contained  in  ordinary  steel  is  very  small,  approxi- 
mately 0.02  per  cent  in  Bessemer  steel  and  0.005  per  cent  in  open 
hearth. 


232  ELECTRIC  ARC   WELDING 

From  the  foregoing  it  is  evident  that  to  improve  the  ductility 
of  welds  it  is  necessary  to  eliminate  as  far  as  possible  the  forma- 
tion of  nitrides  and  oxides. 

A  test  recently  conducted,  using  a  certain  type  of  coating  on 
an  ingot  iron  electrode,  showed  a  75  per  cent  reduction  of  nitro- 
gen in  the  weld  over  that  of  welds  made  with  bare  electrodes. 
Many  attempts  have  been  made  to  eliminate  nitrides  and  oxides 
by  the  use  of  elements  which  will  act  as  reducing  agents.  It  ap- 
pears, however,  that  owing  to  the  great  affinity  for  oxygen  and 
nitrogen  of  such  elements  as  would  perform  this  function  they  are 
destroyed  without  much  effect  unless  present  in  quantities  objec- 
tionable in  other  respects. 

Slag  Inclusions. — It  is  self-evident  that  slag  inclusions'  will 
constitute  a  source  of  weakness  in  a  weld.  The  apparent  cause 
of  most  slag  inclusions  is  lack  of  cleaning  the  surface  to  be 
welded,  so  that  the  scale  is  not  always  entirely  fused  before  metal 
deposition  occurs,  in  which  case  if  the  metal  cools  quickly  the 
slag  is  trapped  in  the  weld.  If  the  surface  to  be  welded  is  clean 
and  the  proper  heat  value  and  manipulation  are  used  to  prevent 
unduly  rapid  cooling,  the  slag  will  be  floated  to  the  top  of  the 
deposit  where  it  will  form  a  scale  and  aid  in  preventing  the  oxi- 
dation of  the  surface,  thus  limiting  the  amount  of  dissolved 
oxygen. 

Gas  Pockets. — The  exact  nature  and  origin  of  the  gases 
trapped  in  welds  has  not  been  definitely  determined.  The 
presence  of  carbon  in  any  appreciable  amount  is  known  to  pro- 
duce gas  pockets.  This  is  particularly  noticeable  when  welding 
on  medium  high  carbon  steel,  and  is  doubtless  due  to  the  com- 
bination of  the  carbon  with  oxygen,  resulting  in  the  formation 
of  carbon  monoxide  gas,  which  on  account  of  the  rapid  solidifi- 
cation of  the  fused  metal  is  trapped.  When  welding  with  a  low 
carbon  steel  electrode  on  low  carbon  steel  plate  material  the  weld 
is  comparatively  free  from  gas  pockets.  On  increasing  the  arc 
length,  however,  the  tendency  to  form  gas  pockets  is  in- 
creased. Since  low  carbon  steel  absorbs  gas  readily  when  ex- 
posed sufficiently  while  in  a  plastic  state,  a  long  arc  is  very  likely 
the  worst  offender  in  producing  gas  pockets.  Their  occurrence, 
due  to  dissolved  or  occluded  gas  or  the  gas  formed  from  im- 


MISCELLANEOUS  NOTES  AND  DATA  233 

purities  present  in  the  ordinary  electrode  material,  is  thought  to 
be  very  limited,  since  these  gases  are  largely  liberated  as  the 
metal  passes  through  the  arc. 

Crystal  Structure. — The  crystal  formation  is  dependent 
largely  upon  the  rate  of  cooling,  and  consequently  upon  the  se- 
quence of  depositing  the  metal;  a  very  fine  grain  is  produced  if  the 
metal  is  cooled  quickly  enough  to  prevent  the  formation  of 
columnar  crystals.  By  adding  the  metal  in  layers,  each  succeed- 
ing layer  tends  to  anneal  the  preceding  one,  thus  effecting  a 
better  structure.  A  refinement  of  the  structure  may  be  obtained, 
as  in  the  case  of  any  cast  metal,  by  heating  and  hammering,  but 
this  is  not  usually  practicable. 

Structural  Disturbance  of  Part  Welded. — The  heat  does  not 
largely  affect  the  surrounding  material  on  plate  stock  of  the  usual 
composition  and  thickness  up  to  at  least  24  in.  The  structure  is 
disturbed  but  little,  1-16  in.  from  the  edge  of  the  weld.  When 
welding  parts  of  larger  sections,  having  a  greater  thermal  capacity 
or  of  higher  carbon  content,  consideration  should  be  given  to  the 
thermal  disturbances. 

The  nature  of  the  service  for  which  the  part  is  intended  will 
determine  the  course  of  action  required.  When  the  carbon  con- 
tent is  as  much  as  .3  per  cent  and  the  section  is  such  as  to  cause 
quick  cooling,  annealing  will  likely  be  necessary,  if  the  part  is  to 
be  subjected  to  vibratory  stresses,  or  if  it  is  to  be  machined 
through  the  line  of  weld.  It  is  advisable  to  investigate  each  case 
and  determine  the  treatment,  according  to  the  magnitude  of  the 
heat  effect  and  service  requirements  of  the  part. 

Microscopic  Examination  of  Weld. — The  following  results 
were  obtained  from  a  microscopic  examination  made  of  some 
metal  deposited  by  the  metallic  arc  process  on  a  ^  in.  piece  of 
,  boiler  plate  steel,  about  2}4  in.  by  1J4  in-  m  size-  The  weld 
was  made  with  a  mild  steel  electrode.  Cuts  made  through  this 
weld  in  obtaining  specimens  for  the  microscope  showed  perfect 
union  of  the  deposit  metal  with  the  steel  plate  with  no  distinct 
boundary  between  them.  Small  holes,  however,  could  be  seen  in 
the  weld  metal  after  the  cut  was  made. 

Three  sections  through  the  deposited  metal  were  cut  at  right 
angles  to  each  other — two  of  them  also  including  portions  of  the 


234 


ELECTRIC  ARC   WELDING 


steel  base — and  were  polished  as  usual  for  the  microscope. 
When  examined  before  etching,  the  deposited  metal  was  seen  in 
each  section  to  be  full  of  very  small  particles  of  iron  oxide,  and 
the  steel  plate  showed  a  large  quantity  of  alumina  with  a  little 
slag.  Photomicrographs  showing  these  inclusions  are  shown. 
When  etched  with  nitric  acid  the  deposited  metal  was  seen  to 
contain  abundant  small  pale  angular  needles  or  crystals  which, 
it  was  thought,  might  be  cementite,  martensite,  or  nitride,  as  the 
needles  commonly  found  in  steel  fusion  welds  have  been  identi- 
fied by  various  authorities  as  each  of  these  substances.  A  portion 
of  the  deposited  metal  was  filed  off  this  sample  without  removing 


FIG.  158— Typical  Structure  of  Plate  Just  Below  Weld,  Etched  with  Nitric 
Acid  and  Magnified  400  Diameters 

any  appreciable  quantity  of  the  underlying  steel  base,  and  an 
analysis  of  the  filings  showed  0.04  per  cent  carbon.  Since  the  de- 
posited metal  was  shown  to  be  practically  homogeneous  by  exam- 
ination in  three  planes  at  right  angles  to  each  other,  it  is  evident 
from  the  low  carbon  content  that  the  needles  or  crystals  cannot  be 
cementite  or  martensite. 


MISCELLANEOUS  NOTES  AND  DATA 


235 


^9 — Typical    Structure    of    Plate    a    Slight   Distance    Below    Weld, 
Etched  with  Nitric  Acid  and  Magnified  400  Diameters 


FIG.  160— Typical  Structure  of  Plate  Beyond  the  Influence  of  the  Weld, 
Etched  with  Nitric  Acid  and  Magnified  400  Diameters 


236  ELECTRIC  ARC   WELDING 

The  steel  plate  below  the  welded  metal  showed  interesting 
variations  of  structure,  some  of  which  are  illustrated  by  photo- 
micrographs. Directly  below  the  weld  the  structure  was  very 
coarse,  and  showed  sorbite  or  troostite  in  angular  arrangements 


FIG.  161— Average  View  of  Deposited  Metal  of  the  Weld,  Unetched  and 
Magnified  400  Diameters,  Showing  Abundant  Fine  Globules  of  Iron 
Oxide 


as  in  a  casting.  Further  down  the  structure  became  gradually 
finer  until  it  was  very  fine,  with  many  small  particles  of  sorbite. 
This  fine  structure  passed  gradually  into  the  original  structure  of 
the  plate  by  coarsening  of  both  sorbite  and  ferrite,  and  trans- 
formation of  some  of  the  former  into  pearlite. 

Annealing  experiments  were  conducted  on  small  sections  of  this 
plate,  including  the  welded  metal,  to  investigate  the  structural 
changes  that  would  take  place.  One  specimen  was  heated  at 


MISCELLANEOUS  NOTES  AND  DATA 


237 


about  500  deg.  C.  for  two  hours,  and  cooled  in  lime.  The 
various  zones  in  the  steel  plate  which  were  described  above  were 
not  changed  perceptibly  by  this  treatment,  but  the  nitrite  in- 
clusions in  the  deposited  metal  showed  a  decided  change.  After 
polishing  and  etching  in  the  same  way  as  before,  these  inclusions 


FIG.  162 — One, of  the  Worst  Streaks  of  Alumina  Inclusions  Seen  in  the 
Steel  Plate,  Unetched  and  Magnified  200  Diameters 

appeared  in  the  form  of  needles,  much  darker,  thinner,  and 
sharper  than  before  the  annealing,  having  somewhat  the  appear- 
ance of  very  fine  angular  pearlite  or  sorbite.  These  structures 
before  and  after  annealing  are  illustrated  by  photomicrographs. 

Another  similar  specimen  was  annealed  at  900  deg.  C.  for  four 
hours  and  cooled  slowly  in  the  furnace.  After  polishing  and  etch- 
ing with  nitric  acid  as  before,  the  nitride  in  the  deposited  metal 
was  seen  to  have  partly  segregated  into  irregular  shaped  bodies 


238 


ELECTRIC  ARC   WELDING 


. 


FIG.  163 — Typical  Structure  of  Deposited  Metal  of  the  Weld  after  Anneal- 
ing at  900  Deg.  C.  for  Four  Hours,  Showing  Oxide  and  Nitride. 


FIG.  164— Structure  of  Narrow  Zone  Between  Weld  and  Plate  after 
Annealing  as  Above  (See  Fig.  163),  Showing  Pearlite  and  Nitride 
in  Ferrite 


MISCELLANEOUS  NOTES  AND  DATA 


239 


resembling  the  segregated  cementite  in  annealed  low-carbon  steel 
sheets.  The  centers  of  some  of  these  bodies  were  dark,  but  were 
not  the  same  as  pearlite,  as  can  be  seen  from  the  photomicro- 
graphs. Some  of  the  needles  of  nitrides  were  present  here  also, 
and  were  darkened  by  the  etching  as  in  the  sample  annealed  at 
the  lower  temperature. 

The  steel  plate  after  the  900  deg.  annealing  lacked  the  dif- 


FIG.  165 — Typical  Structure  of  Steel  Plate  below  Weld  after  Annealing 
as  Above  (Fig.  163),  Showing  Pearlite  in  Coarse  Ferrite  Without 
Nitride 

ferent  zones  described  in  the  original  welded  plate,  but  was  com- 
posed entirely  of  ferrite  and  pearlite,  both  coarsened  by  the  heat- 
treatment.  A  narrow  border  between  the  deposited  metal  and  the 
steel  plate  contained  both  pearlite  and  nitride  needles,  which 
could  readily  be  distinguished  from  each  other,  thus  furnishing 
further  proof  that  the  original  inclusions  in  the  deposited  metal 
were  not  a  carbide  product  such  as  cementite  or  martensite. 

The  presence  of  alumina  inclusions,  which  of  course  do  not 
migrate  by  diffusion  on  annealing,  in  this  boundary  zone  con- 
taining both  pearlite  and  nitride,  showed  that  it  was  the  nitride 


240 


ELECTRIC  ARC   WELDING 


that  diffused  into  the  steel  plate  below  the  weld.  The  abrupt  ter- 
mination of  the  pearlite  particles  at  the  upper  boundary  of  this 
zone  showed  that  the  oxide  and  nitride  in  the  deposited  metal  had 
prevented  any  diffusion  of-  carbide  into  it  from  the  steel  plate  be- 
neath. 

These  experiments  show  that  while  the  chilling  effect  of  the 


FIG.  166 — Typical  Structure  of  Deposited  Metal  of  the  Weld  as  Received, 
without  Annealing,  Showing  Round  Gray  Oxide  Spots,  and  Pale 
Angular  Nitride  Crystals 


welding  on  the  structure  of  steel  plates  can  be  removed  by  anneal- 
ing, the  idea  that  nitrogen  can  be  so  removed  is  erroneous.  On 
the  contrary,  support  is  given  to  the  opposite  view  that  although 
steel  does  not  easily  absorb  nitrogen  during  ordinary  heat-treat- 
ments, neither  is  this  element  readily  removed  when  once  it  has 
been  absorbed. 


MISCELLANEOUS  NOTES  AND  DATA 


241 


Strength  of  Weld. — A  competent  operator,  using  bare  elec- 
trodes of  mild  steel  or  ingot  iron  should  consistently  produce 
welds  having  an  average  tensile  strength  of  40,000  Ib.  per  square 
inch.  The  ductility  of  the  average  weld  is  poor,  due  to  reasons 


FIG.  167— Typical  Structure  of  Deposited  Metal  of  the  Weld  after  Anneal- 
ing at  500  Deg.  C.  for  Two  Hours,  Showing  Nitride  Needles  Dark- 
ened by  the  Etching,  and  Round  Oxide  Dots  Unchanged 

previously  described.  A  capable  operator  should  produce  a  weld 
having  an  elongation  of  5  per  cent  and  a  reduction  in  area  ex- 
ceeding 7  per  cent.  Further  data  are  given  on  this  subject  in  the 
table  of  the  Wirt- Jones  investigation  of  J^  in.  arc  welded  ship 
plates;  it  will  be  noted  that  the  above  figures  are  conservative, 
since  they  are  intended  only  to  show  the  reliance  which  may 
safely  be  placed  in  the  process,  when  using  the  most  ordinary 
materials. 


242 


ELECTRIC  ARC   WELDING 


The  tabulation  of  results  of  test  shown  were  conducted  to 
determine  the  efficiency  of  metallic  arc  welded  joints  on  half -inch 
ship  plates  with  different  systems  and  types  of  electrodes.  A 
study  of  this  sheet  will  show  quite  conclusively  what  may  be  ex- 
pected of  a  welded  joint.  The  authors  have  compared  this  test 
with  considerable  other  test  data  and  find  that  the  results  shown 
are  representative  of  that  obtained  in  a  number  of  other  instances 
where  similar  investigations  have  been  made. 

Speed  and  Cost  of  Arc  Welding. — Speed  of  arc  welding  for 
seams  or  joints  is  usually  expressed  in  feet  per  hour  for  a  given 
thickness.  For  building-up  operations  and  the  like  the  speed  of 
welding  is  expressed  in  pounds  of  metal  used  or  deposited  per 
hour. 

It  is  difficult,  in  either  case,  to  give  information  in  a  form 
which  can  be  used  accurately  to  estimate  the  time  required  for  a 
given  operator,  as  the  available  data  on  this  subject  at  the  present 
time  are  not  sufficiently  complete.  The  reason  more  information 
is  not  available  will  better  be  appreciated  when  consideration  is 
given  to  the  many  factors  which  determine  the  speed  of  weld, 
such  for  example  as  the  type  of  joint,  angle  of  bevel,  spacing, 
position  of  work,  electrode  size,  electrode  current  density, 
whether  work  is  inside  or  out  in  the  open,  efficiency  of  operator, 
etc.  It  is  not,  however,  a  difficult  matter  to  secure  the  speed  of 
welding  for  any  given  operation  under  given  conditions. 

The  following  tables  will  give  some  idea  as  to  the  rate  of 
welding  for  different  plate  thickness,  arc  currents,  and  electrode 
sizes : 

DATA  ON  SEAMS  OF  REGULAR  PRODUCTION  WORK 


Plate 
Thick- 
ness 
Inches 

Diameter 
Electrode 
Inches 

Time  in 
minutes 
per  straight 
foot 

Pounds  wire 
used  per 
foot 
welded 

Arc 
Cur- 
rent 

% 

1 

% 
% 
% 
% 

V* 

I 
t 

& 
& 

30. 
25 
20 
25 
35 
33 
45 

.5 
.6 
.5 
.68 
1.5 
1.3 
1.75 

70 
70 
120 
130 
160 
135 
180 

U.S.  SHIPPING  BOARD 
EMERGENCY  FLEET  CORPORATION 
ELECTRIC  WELDING  COMMITTEE 

PLATES  TESTED  BY  DIVISION  VIH  AND  VIII 

BUREAU  OF  STANDARDS-  WASHINGTON,  D.C. 

1        1 

TE 

WIRT  ~  JONES    INVESTIGATION 
ONE-HALF  INCH  ARC°WELDED  -SHIP  PLATES 

YIELD  POINT        E 
LB.  PERSQ.  IN.     21 

WELD 

38,400 

8 

||_I^2{SJ£L 

ie 

17 

5) 

21 

Z2 

V  \  Z8 

Z9    |  30 

33 

SERIAL  NO. 
OF 
COMMITTEE 

WELD 

ELECTRODE 

POWER 

REMARKS  ON 
WELD 

i 

POSITION 

Ul 

a. 

RATE  IN 
FT.  HOURS 

Ul 

a. 
t- 

i 

<z 

MANUFACT'R 
OF 
ELECTRODE 

CURRENT  IN 
AMPERES 

VOLTAGE 

<£ 

£fin 

j 

A.C. 

D.C. 

OPEN 
CIRCUIT 

ARC 

u. 

^ 

I 

R.B. 

/ 

U|^J 

3.35 

.15^5 

ROEBLING 

170-180 

67-68 

18-22 

Each  Weld  made  in  1  rur 
Plates  cleaned  by  sand  t 

2 

u 

y 

,;'/2 

2.86 

- 

I 

150-160 

67-68 

18-22 

Each  Weld  made  in  1  ro 
Plates  cleaned  t>M  sand  I 

3 

G.D.W. 

y 

« 

2.35 

AM.BflSI 
ANNEAL 

0    " 

AM.  STEEL 
&WIRE 

110-120 

63 

14-17 

4 

u 

y 

H 

3.64 

N 

.1875 

N 

140 

63 

15 

5 

•j 

H 

4.44 

.15625 

,| 

I40HSO 

75 

18-20 

Each  Weld  made  in  Iro 

* 

y 

II 

3.99 

• 

II 

140-150 

75 

18-20 

Each  Weld  made  in  2  ru 

7 

J.W. 

y 

I 

3.16 

.125 

ROEBLING 

IIO-I2C 
ISO 

65 

18-20 

First  side  of  plate  was  we 
using  IIO-IEOAmp.otherside  15 

8 

u 

y 

n 

2.56 

.125 

u 

110-120 

<bS 

18-20 

9A 

HINES 

/ 

. 

3.68 

.1875 

ARMCO 

150 
60  CYCLE 

117 

20-22 

9 

1 

y 

. 

2.78 

TONOW 

.15625 

WASH  BURN 
WIRE  CO. 

150 

75 

19 

10 

i. 

y 

n 

3.00 

II 

• 

1 

ISO 

75 

19 

1  1 

H.W.S. 

y 

« 

1.81 

n 

ROEBLING 

140 

37.5 

18-22 

Each  plate  welded  with  Z  r 
on  1st.  side,  1  run  on  ^nd.s 

)Z 

- 

y 

• 

2.49 

a 

« 

140 

37.5 

18-22 

Each  plate  welded  with  2 
on  Ist.side.lron  on  2nd.S 

13 

P.K. 

y 

« 

3.07 

SIElW 
VYELDIN 

J          " 

S.&W.CO. 

150-160 

63 

24-28 

14 

„ 

y 

n 

2.85 

WIRE 
n 

. 

u 

I45-IS5 

63 

20-22 

15 

D.B.T. 

y 

„ 

1.53 

COATED 

.134 

Q..A. 

90 

110 

35 

Weld  made  in  2  runs 

\<b 

• 

y1 

. 

1.81 

• 

. 

* 

90 

110 

35 

"     " 

17 

J.M.M. 

y 

, 

1.37 

n 

4 

n 

90 

102. 

35 

„           „        .    .     « 

18 

. 

y 

. 

1.81 

H 

. 

* 

90 

102 

35 

.         „    .     . 

19 

J.J. 

y 

u 

1.90 

, 

.125 

Q.A. 

150 

fcOCYCLE 

115 

20-25 

Weld  made  in  2  runs 
Current  used  1.Z6K.W.H 

ZO 

. 

y 

• 

1.48 

BARE 

.125 

E.A.C.& 
W.CO. 

175 
60CYGLE 

J25 

J5 

Weld  made  in  ^i.  runs 
Current  used  1.6  K.W.H 

Zl 

T.T. 

/ 

1 

1.59 

COATED 

.134 

Q.A. 

105 

E5CYCLE 

too 

40 

Input  5.6  K.W.-I.27K.W.H 

^^ 

J.J. 

y 

II 

.97 

Jfc. 

.125 

E.A.C.& 
W.CO. 

160 
ZSCYCU 

too 

^o  >^ 

/•Operator's  first  experien 
with  25cycle  and  lostcon 
able  time  cleaning  outi 
and  changing  electro* 
Weld  made  in  2  runs-t 
was  considerable  sputt 
when  welding.  Inputs 

Z3 

E.L.C. 

y 

H 

2.10 

. 

ROEBLING 

80-90 

63 

18-20^ 

Z4 

J.W.F. 

y 

• 

1.90 

. 

n 

80-85 

63 

I8-2O 

ZS 

N 

y 

. 

3.19 

.15615 

. 

60CYCU 

115 

/S-2O 

ZQ 

n 

/ 

n 

2.66 

.125 

n 

A 

230 

17 

Z7 

M.B.K. 

/ 

1 

2.85 

. 

• 

1(0 

78 

20-22 

Z8 

H 

y 

N 

2.66 

u 

n 

110 

78 

20-22 

Z9 

J.G. 

/ 

»- 

3.35 

.15625 

W.W.8iM.CO. 

150 

55-37 

18-20 

30 

u 

/ 

II 

2.59 

a 

• 

135 

35-37 

18-20 

31 

OARAW 

^ 

. 

3.84 

.166 

ROE  BUNG 

ISO 

20 

Welded  1  run  each  sid< 

3Z 

• 

J 

• 

3.12 

u 

. 

UJ 

ISO 

^o 

Welded  2  runs  each  si 

37(104  &) 
38004C) 

J.J. 
J.J. 

•/ 

1 

1:!! 

COYEREI 

.1250 

E.A.CO. 

\Z5  & 
ISO  § 

Is 

Note:Columns9,IO,l8.l9,Z5,Z4,Z5,2e,3l,32,34,35,3e,S7  Omitted  due  J 
Column  No.l7-Ratincj  in  ft.hrs.  is  total  time  for  welding  bo 

o  lack  of  data, 
•h  sides  of  plate. 

TEST  OF  PLATE  MATERIAL  (AVERAGE  OF  TWO  TESTS) 

3 

4 

5 

<b 

7 

E    TEST 

TORSION   TEST 

VIBRATION  TE51 

BENDING  TEST 

riON   IN 
PERCENT 

ULTIMATFSTREM6TI 
LB.  PER  SQ.IN. 

ANGULAR  DEGREES 
OF  PLATE 

TORQUE  OF  PLATE 
INCH  RADIUS  LB. 

NO.OF  OSCILLATIONS 
OF  PLATE 

ANGULAR  DEGREES 
OF  PLATE 

5 

64,700 

574 

6,048 

O.K.  for  180° 

38 

39 

40     |4i 

42. 

43 

44 

45 

A 

\ 

47 

48 

49 

SO 

51 

SZ 

TENSILE  TEST 

TORSION  TEST 

VIBRATION  TEST 

BENDING  T. 

REMARKS  ON 
TEST 

IELO 
DINT 

ELON. 
IN21N, 

ULTIMATE 

WELD 

RATIO  IN 
PER  CENT 

WELO 

RATIO  IN 
PER  CENT 

fc|£z 

111 

RATIO  IN 
PERCENT 

WELD 

O;OL 

TESTER'S 
SERIAL  NO 

ANGULAR 
DEGREES 

u     03 

ANGULAR 
DEGREES 

3.PFR 
Q.IN. 

PER 
CENT 

LB.  PER 
SQ.IN. 

5400 

9.0 

59800 

443 

11.1 

5338 

88.3 

42 

23.3 

H.J.C. 

9000 

11.5 

6Z60O 

464 

80.8 

5512 

91.1 

44 

24.4 

B 

o300 
4300 

13.0 
5.0 

65470 
50600 

* 

322 

56.1 

4728 

78.1 

34 

18.9 

5  500 
J650 

7.0 
8.5 

52280 
61100 

• 

306 

53.3 

4620 

76.4 

55 

30.6 

„ 

06  00 
3000 

7.0 
8.5 

53700 
57600 

403 
454 

/0.3 
79.Z 

4583 
5154 

75.7 
85.  E 

45 
50 

25.0 
27.8 

" 

4-500 
4300 

13.5 
14.0 

59400 
58200 

645 
518 

90.3 

5468 
5121 

90.5 
84.6 

60 

33.3 

" 

Fractured  2"  from*.  of 
weld  in  tensile  test 

i/00 

4500 

4.0 
4.0 

42500 
36300 

194 

33.8 

3732 

61.6 

30 

16.7 

• 

4.0 
4.0 

38100 
44200 

262 

45.  9 

3732 

<6\.<c 

15 
26 

8.3 
14.4 

" 

1800 
£300 

4.5 
4.5_, 

41300 
41900 

^\^ 

36.9 

3385 

56.0 

25 
24 

13.9 
13.3 

" 

i4eo 

8.0 

4.0 

57340 
39400 

* 

ze| 

45.5 

4080 

67.5 

30 

16.7 

(l 

J280 
B400 

5.25 
7.00 

58740 
50Z50 

* 

441 

76.8 

4788 

7&2 

25000 
50000 

ks.636JE 
31,320 

) 

35 

19.9 

„ 

Failure  only  offer  fi  ber  stress 
had  been  increased  to  50.000 

34«0 
7500 

11.0 
6.0 

61760 
54000 

• 

2J6 

37.6 

3900 

64.5 

<b5 

36.1 

„ 

/ooo 

7200 

6.0 
12.0 

65400 
^800 

* 

320 

55.8 

4332 

71.6 

32 

17.8 

, 

Fractured  3.2"  from  4-of  weld 
in-hensi  le  testCweld  notmach'rid) 

ESxi 

2400 

11.0 
9.0 

66480 
62700 

* 

425 

74.0 

5381 

88.9 

35000 

4..320.00C 

34 

18.9 

m 

Fractured  6.2"from4.of  weld 
in+ensi  le  testtweld  notmach'rid 

3700 

5.0 

42200 

4Z 

Z3.S 

* 

3000 
7100 

9.0 
6.0 

66400 
50000 

• 

^74 

47.7 

4596 

76.0 

78 

43.4 

. 

Fractured  6-5"  from*,  of  weWI 
in  tensi  le  tesKweld  not  mach'n'd  ) 

7850 

5.0 
4.0 

57060 
51900 

• 

238 
249 

Si 

4#<5 

71.1 
69.1 

25000 

14.645.51 

0 

800 

6.0 

45400 

191 
148 

33.3 
25.8 

4296 
3541 

71.0 
58.5 

25000 

seo.iso 

IS 

8.3 

„ 

4/00 
5300 

4.0 
3.5 

47800 
43700 

* 

£45 

47.2 

4128 

35000 

89.577 

Z<& 

14.4 

„ 

3.0 

34200 

lok 

!«'$ 

ft7? 

25000 

U2S.no 

IS 

6.3 

„ 

ll'JU 

0600 

7.0 
8.0 

48200 
45800 

* 

465 

8I.| 

4668 

77.  Z 

42 

23.3 

„ 

. 

&800 
7200 

6.5 
6.0 

56400 
54400 

397 

486 

69.2 
84.7 

5159 
5380 

8S.Z 
88.9 

47 

16.1 

s 

d/00 
2100 

II.  0 
10.5 

53ZOO 
52000 

•f 

453 

534 

93^ 

4762 
4498 

78.7 
74.  S 

50 

^7.6 

n 

•»-  Fractured  2.5"  from  <t  of 
weld  in  tens!  latest 

3500 

8.0 

60900 

iltt 
450 

90.4 
78.4 

6288 
5856 

104.0* 
96.8 

-ractured  5.2"  from<t  of  weld  ir 
Torsion  Test  tweld  not  mach'n'd  } 

73W 
5400 

490 

85.4 

5568 

92.1 

25000 

537600 

, 

58 
71 

32.2 
39.4 

Fractured  in  material  atedge 
of  weld  (.VibrationTest) 

7.0 
7.0 

56400 
54500 

520 

290 

55.7 
50.5 

4557 
4557 

75.4 
75.4 

42 
45 

Z3.3 
2.5.0 

• 

:  Yield  Point  from  Beam  Drop.           Values  recorded  are  results  of  individual  tests. 
Weld  not  machined  marked  • 

MISCELLANEOUS  NOTES  AND  DATA  243 

RESULTS   OBTAINED  ON   y2  IN.   PLATE  WITH   &   IN.   DIAMETER  ELECTRODE 


Arc 
Cur- 
rent 

Feet 
welded 
per  hr. 

Lbs.  wire 
used  per 
hour 

Lbs.  wire 
used  per 
foot 

Percentage 
scrap 
ends 

Percentage 
time  oper. 
welding 

150 

2.4 

2.45 

1.02 

12.2 

58 

140 
150 

2.9 
4.6 

1.43 
1.8 

.49 
.38 

13 
11.1 

58 
70 

150 
140 

4.12 
4.9 

2.6 
2.1 

.62 
.43 

10.3 
10 

58 
70 

150 
150 

3 
3 

2.0 
1.8 

.66 
.51 

9.7 
8.3 

58 
62 

165 
150 

2.4 
4.6 

2.38 

2.5 

.98 

.52 

8.6 
12.1 

58 
70 

The  cost  of  electric  welding  varies  widely  for  different  work. 
The  cost  of  making  the  weld  can  best  be  figured  on  the  basis  of 
average  kilowatt  hours  per  pound  of  metal  used  or  consumed  for 
each  make  of  equipment.  -For  modern  equipment  this  will  be 
approximately  2.5  k.w.  per  pound  of  metal  used. 

By  determining  the  average  efficiency  of  the  welding  equipment 
in  k.w.  hours  per  pound  of  metal  used,  the  cost  for  any  given 
welding  operator  can  be  obtained  from  the  record  of  the  time  in 
hours  required  to  perform  the  weld  and  the  weight  of  metal  used 
in  pounds.  This  can  then  be  reduced  to  cost  per  hour  or  per  foot 
of  weld,  as  desired. 

The  following  is  the  result  of  a  test  conducted  on  an  arc  weld- 
ing equipment  and  coated  electrodes  to  determine 

(1)  K.w.  hr.  per  pound  of  metal  used  or  deposited. 

(2)  Waste  of  electrode  material  in  stub  ends  and  vapor,  in- 
cluding the  metal  thrown  off  by  the  arc. 

(3)  Pounds  of  metal  per  hour  that  can  be  deposited  with  a 
given  electrode  diameter  and  current  value. 

The  data  shown  below  were  arrived  at  by  depositing  metal  on  a 
y%  in.  piece  of  boiler  plate  of  known  weight,  with  3/16  in.  di- 
ameter coated  electrodes,  which  were  weighed  before  being 
coated.  When  sufficient  metal  to  give  accurate  readings  had  been 
deposited,  the  plate  and  electrode  material,  including  stub  ends 


244  ELECTRIC  ARC   WELDING 

left  over,  were  again  weighed.  The  coating  was  removed  from 
the  electrodes  so  that  its  weight  would  not  be  included. 

The  power  consumed  during  the  test  was  recorded  by  a  test 
meter,  which  gave  an  accuracy  of  power  consumed  within  a 
fraction  of  a  watt. 

The  weld  was  made  in  one  layer  on.  the  plate  and  all  the  scale 
was  thoroughly  removed  from  the  weld  before  the  plate  was 
weighed. 

The  welding  was  done  in  a  building  where  there  was  a  slight 
draft. 

The  results  in  detail  were  as  follows  : 

Weight  of  work  piece  assembled  for  test 30.1562  Ib. 

Weight  of  electrodes  assembled  for  test 2.5312  Ib. 

Duration  of  test  started  at  10:08 — finished  at  10:41 33  mih. 

Current  in  arc — average 140  amp. 

Voltage  across  arc — average 21  volts 

Power  consumed  during  test 2,976.9  watt  hrs. 

Weight  of  plate  after  test 31.4062  Ib. 

Weight  of  electrodes  left  over 9375  Ib. 

Weight  of  electrode  stub  ends 2500  Ib. 

Weight  of  electrode  material  lost  in  vapor  or  thrown 

out   of   arc .0937  Ib. 

Weight  of  metal  deposited  on  plate 1.2500  Ib. 

Weight  of  electrodes  used 1.5935  Ib. 

Rate  of  electrode  material  consumption,  Ib.  per  hour. . . .  2.8920  Ib. 

Rate  of  depositing  metal  on  plate — Ib.  per  hour 2.2700 

Percentage  vapor  loss 5.88 

Percentage  stub  ends 15.70 

Percentage  deposited 78.42 

K.w.  hr.  per  pound  of  metal  used 1.862 

K.w.  hr.  per  pound  of  metal  deposited 2.370 

Note: 

Percentage  vapor  loss  bare  wire 12. 

Diff.  in  vapor  loss  "bare"  and  "coated" 6.12 

Reduction  of  loss — coated  over  bare 51. 

Note: 

The  loss  of  metal  due  to  vaporization  is  charged  entirely  against  the 
electrode.  This,  however,  is  not  strictly  true  as  some  of  the  vapor  is 
emitted  from  the  plate.  This  would  make  the  metal  actually  deposited 
a  little  higher  than  shown,  due  to  the  fact  that  there  had  to  be  suffi- 
cient metal  deposited  to  make  up  for  the  vapor  loss  on  the  plate. 

ESTIMATED  CONSTRUCTION  COST  OF  166  FT.  BY  39  FT.  BY  8  FT.  8  IN.  BARGE 

Items  Riveted  Design  Welded  Type 

Plate   Fitters    $1,236.00  $618.00 

Punching  and  Shearing 1,045.00  522.00 

Countersinking   and    Reaming 976.00 

Riveting   3,427.00 

Chipping  and  Caulking 523.00  265.00 


MISCELLANEOUS  NOTES  AND  DATA  245 

Smithwork                                      557.00  275.00 

Assembling    '               V  2,010.00  1,320.00 

ElectHc  Power   I! 382.00**  95.00* 

Foreman    360.00  360.00 

Plant    300.00 

Superintendence    900.00 

Rivets    780.00 

Liners   142.00 

Shed  and   Shoring   Lumber 145.00 

WELDING — ASSEMBLING  AND  CONSTRUCTION 

51,300  ft.  Single  Fillet- 
Welders— 6,000  hr.  @  60c $3,600 

Current— 6,000  x  5 

30,000  K.W.  H.  @  2%c 750 

Wire— 7,200  Ib.  @  6V2c 450 

4,800.00 

Incidentals    250.00 

Profit    1,000.00 

Total .$11,438.00  $10,850.00 

*  Current  used  for  lighting,  punching,  shearing  and  air  compressor  only. 
**  Figures  for  riveted  design,  based  on  actual  cost  of  three  barges  com- 
pleted during  preceding  month. 

COMPARATIVE  DETAILS  OF  RIVETED  AND  RIVETLESS  SHIP  STRUCTURES  DEVEL- 
OPED BY  MEASUREMENTS  OF  ACTUAL  BILGE  SECTIONS 

Ref.                  Particulars                                       Riveted  Welded 

A     Weight  of  Plates  required 2488  Ib.  1884  Ib. 

B     Weight  of  Angles,  Beams  and  Channels     764  Ib.  194  Ib. 

C     Weight  of   Straight  Bars none  360  Ib. 

D     No.  of   %  in.  Rivets 48  none 

E     No.  of   %   in.  Rivets 231  none 

F     No.  of  %  in.  Rivets 108  none 

G     Total  No.  of  Rivets 387  none 

H    Total  Weight  of  Rivets 200  Ib.  none 

I       No.  of  Liners  required 4  none 

J      Weight  of  Liners 31  Ib.  none 

K     Weight  of  Weld  material  added none  120  Ib. 

L     Total  weight  of  complete  section 3483  Ib.  2558  Ib. 

M    Lineal    Feet   of    Heavy    Flanging   and 

Shaping 22  none 

N     Sq.  ft.  of  Forge  Shaped  Bilge  Plate...       24  none 

O     Sq.  ft.  of  Machine  Rolled  Bilge  Plate.,  none  20 
P     No.  Lineal  feet  of  welds  in  terms  of 

x/4  sq.  in.  Section none  620 

Q     No.  Lineal  feet  of  Caulked  Edges 57  none 

R     Total  No.  of  all  Rivet  Holes  in  Section    826  none 
S      Average  Area  of  Plates  of  full  size. . .  17280  sq.  in.  15235  sq.  in. 

T     Average  No.  of  Rivet  Holes  in  same . . .     550  none 

From  a  report  contributed  by  W.  T.  Bonner,  of  Chester  Ship  Building 
Co.,  to  the  Emergency  Fleet,  Corporation. 


246  ELECTRIC  ARC   WELDING 

METALLURGY  OF  IRON  AND  STEEL 
{Reproduced  from  the  Iron  Age) 

IRON  ORE  contains  Iron  and  Oxygen  and  impurities. 

IRON  ORE  smelted   in   Blast  Furnace   removing   Oxygen   and   part   of 

impurities   and  adding   Carbon,   makes   Pig  Iron. 

FOUNDRY  PIG  IRON  melted  in  Cupola  and  cast  makes  Iron  Castings. 
IRON  CASTINGS  made  from  Malleable  Pig  Iron  and  heated  in  Scale, 

make  Malleable  Castings. 
GREY  FORGE  PIT  IRON  melted  in  a  Puddling  Furnace,  then  balled, 

squeezed  and  rolled,  makes  Muck  Bar. 

MUCK  BAR,  treated  as  above  and  rolled  into  strips,  makes  Skelp  Iron. 
SKELP  IRON  bent  into  the  shape  of  Tubes  and  welded,  makes  Iron  Pipe. 
MUCK  BAR  or  Steel,  melted  in  a  Crucible  with  Charcoal,  makes  Carbon 

Steel,  Tool  Steel,  or  Crucible  Steel. 
MUCK  BAR  or  Steel,  treated  as  above  with  Tungsten  added  to  raise  the 

temperature    at    which    it    softens,    Chromium   to   give    toughness,    and 

Vanadium,  Titanium,  Aluminum  or  other  metals  to  improve  the  quality, 

heated  to  a  high,  then  to  a  lower  heat,  makes  High  Speed  Steel. 
BESSEMER  PIG. IRON  direct  from  Blast  Furnace  or  melted  in  Cupola, 

poured  into  Converter  with  air  blown  through  it  to  burn  out  the  impuri- 
ties, makes  Bessemer  Steel. 
PIG  IRON  molten,  or  in  Pig,  with  or  without  Scrap,  when  purified  in 

Op(en-Hearth  Furnace,  makes  Open-Hearth  Steel. 
LOW  PHOSPHORUS  PIG  IRON,  treated  as  above  in  an  Acid-Lined 

(Silica  or  Sand)  Furnace,  makes  Acid  Open-Hearth  Steel. 
BASIC  PIG  IRON  treated  as  above  in  a  Basic-  (Dolomite)  Lined  Furnace 

to  remove  Phosphorus,  makes  Basic  Open-Hearth  Steel. 
BASIC  OPEN-HEARTH  MATERIAL  with  only   about   1/10  of  1  per 

cent  impurities  is  American  Ingot  Iron,  and  Genuine  Open-Hearth  Iron. 
VANADIUM   STEEL  or  Manganese    (over  7  per  cent),    Titanium,   or 

Nickel  Steel,  is  made  by  the  addition  of  these  metals,  all  being  called 

Alloy  Steels. 

STEEL,  purified  in  an  Electric  Furnace  makes  High  Grade  Steel. 
STEEL  is  cast  into  Ingot  Molds,  usually  about   19  inches   square,  and 

about  6  feet  long,  making  Ingots. 
INGOTS  are  rolled  into  Blooms  or  Billets. 
BLOOMS  are  rolled  into  Rails. 
BLOOMS  are  rolled  into  Structural  Shapes. 
INGOTS  are  rolled  into  Slabs. 
SLABS  are  rolled  into  Plates. 
INGOTS  are  rolled  into  Sheet  Bars. 
SHEET  BARS  are  rolled  into  Sheets. 
SHEETS  are  cold-rolled  and  stamped  into  Forms. 
SHEET  BARS  are  rolled  into  Black  Sheets. 

BLACK  SHEETS  cleaned  and  coated  with  Speller   (Zinc)    make  Gal- 
vanized Sheets. 
BLACK  SHEETS  cleaned,  cold-rolled  and  coated  with   Tin,  make  Tin 

Plate. 
BLACK  SHEETS  cleaned,  cold-rolled  and  coated   with  Lead  and   Tin, 

make  Terne  Plate. 
INGOTS  are  rolled  into  Billets. 
BILLETS  are  rolled  into  Bars  and  Small  Shapes. 
BILLETS  are  rolled  into  Steel  Skelp. 
STEEL  SKELP  bent  into  the  shape  of  Tubes  and  welded  makes  Steel  Pipe. 


MISCELLANEOUS  NOTES  AND  DATA 


247 


BILLETS  are  pierced,  rolled  and  drawn  through  Dies,  making  Seamless 

Tubes. 

BILLETS  are  rolled  into  Rods. 
RODS  are  drawn  through  Dies  into  Wire. 
WIRE  is  made  into  Nails  and  Fencing. 
RODS  are  headed  into  Rivets  and  Bolts. 
RODS  are  welded  into  Chain. 


TEMPER  COLORS  OF  STEEL 
(Hardening,  Tempering,  Annealing  and  Forging  of  Steel — Woodworth) 


Color  of  Oxides 


Temperature,  Deg. 


Cent. 


Fahr. 


Pale   Yellow    220 

Straw    235 

Dark  Straw  or  Golden  Yellow 243 

Brown     255 

Brown,  Dappled  with  Purple 265 

Purple   277 

Bright  Blue  .  288 

Full  Blue   293 

Polish    Blue    304 

Dark  Blue   .  316 

Pale    Blue    321 

Blue,  Tinged  with  Green 332 


428 

455 
470 

491 
509 
530 

550 
560 
580 

600 
610 
630 


248 


ELECTRIC  ARC   WELDING 


CONVERSION  TABLES  OF  FAHRENHEIT  AND  CENTIGRADE  SCALES 

Temperature  Centigrade  —  5/9  (Temperature  Fahrenheit  — 32) 
Temperature  Fahrenheit  —  32  -f-  9/5   (Temperature  Centigrade) 


Cent. 

Fahr. 

Cent. 

Fahr. 

Cent. 

Fahr. 

230 

446 

460 

860 

690 

1274 

235 

455 

465 

869 

695 

1283 

240 

464 

470 

878 

700 

1292 

245 

473 

475 

887 

705 

1301 

250 

482 

480 

896 

710 

1310 

255 

491 

485 

905 

715 

1319 

260 

500 

490 

914 

720 

1328 

265 

509 

495 

923 

725 

1337 

270 

518 

500 

932 

730 

1346 

275 

527 

505 

941 

735 

1355 

280 

536 

510 

950 

740 

1382 

285 

545 

515 

959 

745 

1364 

290 

554 

520 

968 

750 

1373 

295 

563 

525 

977 

755 

1391 

300 

572 

530 

986 

760 

1400 

305 

581 

535 

.  995 

765 

1409 

310 

590 

540 

1004 

770 

1418 

315 

599 

545 

1013 

775 

1427 

320 

608 

550 

1022 

780 

1436 

325 

617 

555 

1031 

785 

1445 

330 

626 

560 

1040 

790 

1454 

335 

635 

565 

1049 

795 

1463 

340 

644 

570 

1058 

800 

1472 

345 

653 

575 

1067 

805 

1481 

350 

662 

580 

1076 

810 

1490 

355 

671 

585 

1085 

815 

1499 

360 

680 

590 

1094 

820 

1508 

365 

689 

595 

1103 

825 

1517 

370 

698 

600 

1112 

830 

1526 

375 

707 

605 

1121 

835 

1535 

380 

716 

610 

1130 

840 

1544 

385 

725 

615 

1139 

845 

1553 

390 

734 

620 

1148 

850 

1562 

395 

743 

625 

1157 

855 

1571 

400 

752 

630 

1166 

860 

1580 

405 

761 

635 

1175 

865 

1589 

410 

770 

640 

1184 

870 

1598 

415 

779 

645 

1193 

875 

1607 

420 

788 

650 

1202 

880 

1616 

425 

797 

655 

1211 

885 

1625 

430 

806 

660 

1220 

890 

1634 

435 

815 

665 

1229 

895 

1643 

440 

824 

670 

1238 

900 

1652 

445 

833 

675 

1247 

905 

1661 

450 

842 

680 

1256 

910 

1670 

455 

851 

685 

1265 

915 

1679 

MISCELLANEOUS  NOTES  AND  DATA  249 

CONVERSION  TABLES  OF  FAHRENHEIT  AND  CENTIGRADE   SCALES — Cont. 


Cent. 

Fahr. 

Cent. 

Fahr. 

Cent*. 

Fahr. 

920 

1688 

1150 

2102 

1380 

2516 

925 

1697 

1155 

2111 

1385 

2525 

930 

1706 

1160 

2120 

1390 

2534 

935 

1715 

1165 

2129 

1395 

2543 

940 

1724 

1170 

2138 

1400 

2552 

945 

1733 

1175 

2147 

1405 

2561 

950 

1742 

1180 

2156 

1410 

2570 

955 

1751 

1185 

2165  • 

1415 

2579 

960 

1760 

1190 

2174 

1420 

2588 

965 

1769 

1195 

2183 

1425 

2597 

970 

1778 

1200 

2192 

1430 

2606 

975 

1787 

1205 

2201 

1435 

2615 

980 

1796 

1210 

2210 

1440 

2624 

985 

1805 

1215 

2219 

1445 

2633 

990 

1814 

1220 

2228 

1450 

2642 

995 

1823 

1225 

2237 

1455 

2651 

1000 

1832 

1230 

2246 

1460 

2660 

1005 

1841 

1235 

2255 

1465 

2669 

1010 

1850 

1240 

2264 

1470 

2678 

1015 

1859 

1245 

2273 

1475 

2687 

1020 

1868 

1250 

2282 

1480 

2696 

1025 

1877 

1255 

2291 

1485 

2705 

1030 

1886 

1260 

2300 

1490 

2714 

1035 

1895 

1265 

2309 

1495 

2723 

1040 

1904 

1270 

2318 

1500 

2732 

1045 

1913 

1275 

2327 

1505 

2741 

1050 

1922 

1280 

2336 

1510 

2750 

1055 

1931 

1285 

2345 

1515 

2759 

1060 

1940 

1290 

2354 

1520 

2768 

1065 

1949 

1295 

2363 

1525 

2777 

1070 

1958 

1300 

2372 

1530 

2786 

1075 

1967 

1305 

2381 

1535 

2795 

1080 

1976 

1310 

2390 

1540 

2804 

1085 

1985 

1315 

2399 

1545 

2813 

1090 

1994 

1320 

2408 

1550 

2822 

1095 

2003 

1325 

2417 

1555 

2831 

1100 

2012 

1330 

2426 

1560 

2840 

1105 

2021 

1335 

2435 

1565 

2849 

1110 

2030 

1340 

2444 

1570 

2858 

1115 

2039 

1345 

2453 

1575 

2867 

1120 

2048 

1350 

2462 

1580 

2876 

1125 

•  2057 

1355 

2471 

1585 

2885 

1130 

2066 

1360 

2480 

1590 

2894 

1135 

2075 

1365 

2489 

1595 

2903 

1140 

2084 

1370 

2498 

1600 

2912 

1145 

2093 

1375 

2507 

250 


ELECTRIC  ARC   WELDING 


METRIC  EQUIVALENTS  OF  COMMON  AND  DECIMAL  FRACTIONS 


Fractions 
of  an  inch 

"Deci- 
mals of 
an  inch 

Milli- 
meters 

Fractions 
of  an  inch 

Deci- 
mals of 
an  inch 

Milli- 
meters 

Ti 

.0156 

0.397 

tt 

.5156 

13.097 

& 

.0313 

0.794 

H 

.5313 

13.494 

A 

.0469 

1.191 

fi 

.5469 

13.891 

& 

.0625 

1.588 

& 

.5625 

14.287 

A 

.0781 

1.985 

H 

.5781 

14.684 

A 

.0938 

•  2.381 

U 

.5938 

15.081 

& 

.1094 

2.778 

If 

.6094 

15.478 

% 

.1250 

3.175 

% 

.6250 

15.875 

A 

.1406 

3.572 

ti 

.6406 

16.272 

A 

.1563 

3.969 

li 

.6563 

16.688 

ii 

.1719 

4.366 

ti 

.6719 

17.085 

& 

.1875 

4.762 

H 

.6875 

17.462 

H 

.2031 

5.159 

ti 

.7031 

17.859 

& 

.2188 

5.556 

§1 

.7188 

18.256 

U 

.2344 

4.953 

ti 

.7344 

1-8.653 

% 

.2500 

6.350 

% 

.7500 

19.050 

H 

.2656 

6.747 

If 

.7656 

19.447 

A 

.2813 

7.144 

§1 

.7813 

19.843 

tt 

.2969 

7.541 

li 

.7969 

20.240 

A 

.3135 

7.937 

it 

.8125 

20.637 

ft 

.3281 

8.334 

H 

.8281 

21.034 

H 

.3438 

8.731 

H 

.8438 

21.430 

H 

.3594 

9.128 

M 

.8594 

21.827 

% 

.3750 

9.525 

7/8 

.8750 

22.224 

if 

.3906 

9.922 

H 

.8906 

22.621 

H 

.4063 

10.319 

M 

.9063 

23.018 

H 

.4219 

10.716 

If 

.9219 

23.415 

A 

.4375 

11.12 

H 

.9375 

23.812 

If 

.4531 

11.509 

fi 

.9531 

24.209 

if 

.4688 

11.906 

li 

.9688 

24.606 

ti 

.4844 

12.303 

fi 

.9844 

25.003 

y2 

.5000 

12.700 

1.0000 

25.400 

MISCELLANEOUS  NOTES  AND  DATA 
COMPARISON  OF  WIRE  GAGES 


251 


No. 

American  "\ 
(B.  & 
B.  &  < 

Vire  Gage 

s.) 

3.  G. 

Stub's 
or 
Birmingh'm 

Washburn 
& 

Old  Eng- 
lish or 
London 

New 
British 

Millimeters 

Decimal 
of  an  inch 

B.  W.  G. 

W.&M. 

O.  E.  G. 

•E.  S.  G. 

0000 
000 
00 
0 

11.684 
10.404 
9.266 
8.252 

.4600 
.4066 
.3648 
.3249 

.454 
.425 
.380 
.340 

.393 
.362 
.331 
.307 

.454 
.425 
.380 
.340 

.400 
.372 
.348 
.324 

1 

2 
3 

4 

7.341 
6.553 
5.826 
5.19 

.2893 
.2576 
.2294 
.2043 

.300 
.284 
.259 
.238 

.283 
.263 
.244 

.225 

.300 
.284 
.259 
.238 

.300 
.276 
.252 
.232 

5 
6 

7 
8 

4.619 
4.115 
3.665 
3.264 

.1819 
.1620 
.1443 
.1285 

.220 
.203 
.180 
.165 

.207 
.192 
.177 
.162 

.220 
.203 
.180 
.165 

.212 
.192 
.176 
.160 

9 
10 
11 
12 

2.906 
2.588 
2.304 
2.052 

.1144 
.1019 
.0907 
.0808 

.148 
.134 
.120 
.109 

.148 
.135 
.120 
.105 

.148 
.134 
.120 
.109 

.144 
.128 
.116 
.104 

13 
14 
15 
16 

1.83 
1.628 
1.45 
1.29 

.0720 
.0641 
.6571 
.0508 

.095 
.083 
.072 
.065 

.092 
.080 
.072 
.063 

.095 
.083 
.072 
.065 

.092 
.080 
.072 
.064 

17 
18 
19 
20 

1.149 
1.0236 
.9115 
.81 

.0453 
.0403 
.0359 
.0320 

.058 
.049 
.042 
.035 

.054 
.047 
.041 
.035 

.058 
.049 
.040 
.035 

.056 
.048 
.040 
.036 

21 

22 
23 
24 

.7239 
.6434 

.574 
.5105 

.0285 
.0254 
.0226 
.0201 

.032 
.028 
.025 
.022 

.032 
.028 
.025 
.023 

.0315 
.0295 
.027 
.025 

.032 
.028 
.024 
.022 

25 
26 
27 
28 

.4547 
.4039 
.3607 
.32 

.0179 
.0159 
.0142 
.0126 

.020 
.018 
.016 
.014 

.020 
.018 
.017 
.016 

.023 
.0205 
.0188 
.0165 

.020 
.018 
.0164 
.0148 

29 
30 
31 

32 

.287 
.254 
.2261 
.2032 

.0113 
.0100 
.0089 
.0080 

.013 
.012 
.010 
.009 

.015 
.014 
.0135 
.013 

.0155 
.0138 
.0123 
.0113 

.0136 
.0124 
.0116 
.0108 

33 
34 

35 
36 

.1803 
.16 
.1422 
.127 

.0071 
.0063 
.0056 
.0050 

.008 
.007 
.005 
.004 

.011 
.01 

.0095 
.009 

.0103 
.0095 
.009 
.0075 

.0100 
.0092 
.0084 
.0076 

37 

113 

.0045 

0085 

0065 

.0068 

38 

1007 

.0040 

008 

0058 

.0060 

39 

0897 

.0035 

0075 

005 

.0052 

40 

0799 

.0031 

007 

.0045 

.0048 

252  ELECTRIC  ARC   WELDING 

PROPERTIES  OF  ELEMENTS  AND  METAL  COMPOSITIONS 


Elements 

Sym- 
bol 

Density 
(  Specific 
Gravity) 

Weight 
Per 
Cubic 
Foot 

Specific 
Heat 

MELTING  POINT 

Degrees 
Centigrade 

Degrees 
Fahrenheit 

Aluminum    
Antimony  .  .    . 

Al 

Sb 

2.7 
6.69 
7.9 
3.51 
6.92 
7.25 
8.89 
19.33 
0.070* 
22.42 
7.865 
11.37 
7.4 
13.55 
8.80 
0.83* 
1.14* 
2.34 
21.45 
0.87* 
2.1 
10.6 
0.971 
2.05 
7.30 
3.5 
18.85 
18.7 
5.5 
7.19 

8.78 
8.60 

8.44 
7.1 

7.8 
7.8 

166.7 
418.3 
490 
219.1 
431.9 
452.54 
555.6 
1205 
.00533 
1400 
490.9 
708.5 
463.2 
848.84 
555.6 
.063 
.0866 
146.1 
1336 
54.3 
131.1 
655.5 
60.6 
128 
455.7 
218.5 
1186 
1167 
343.3 
443.2 

548 
540 

527 
443.2 

486.9 
486.9 

0.212 
0.049 
0.115 
0.113 
0.104 

658.7 
630 
1535 
3600 
1520 
2200 
1083 
1063 
—259 
2300 
1530 
327 
1260 
—38.7 
1452 
—210     |  • 

\2P    \ 
°^4    r  ^ 
1755  4s 
62.3^  v 
1420        f 
960.5 
97.5 
112.8 
231.9 
1795 
3000 

1217.7 
1166 
2795 
6512 
2768 
3992 
1981.4 
1946 
-   —434.2 
,-    4172 
2786 
^       621 
v      2300 
V      —37.6 
2645.6 
?    —346 
—472 
111.2 
3191 
144.1 
2588 
1761 
207.5 
235 
449.5 
3263 
5432 

Carbon    

C 

Cr 
Cb 
Cu 
Au 
H 
Ir 
Fe 
Pb 
Mn 
Hg 
Ni 
N 
O 
P 
Pt 
K 
Si 
Ag 
Na 
S 
Sn 
Ti 
W 
U 
V 
Zn 

Chromium    .... 
Columbium    .  .  . 
Copper    

0.092 
0.032 

'6.032* 
0.115 
0.030 
0.111 
0.033 
0.109 

Gold    

Hydrogen    .... 
Iridium   
Iron    

Lead 

Manganese    .  .  . 
M^ercury 

Nickel    
Nitrogen 

Oxygen    
Phosphorus   .  .  . 
Platinum 

0.19 
0.032 
0.170 
0.175 
0.055 
0.253 
0.173 
0.054 
0.110 
0.034 
0.028 
0.115 
0.093 

Potassium    
Silicon  
Silver    . 

Sodium   .  .  . 

Sulphur 

Tin    

Titanium    .... 
Tungsten 
Uranium 

Vanadium    .... 
Zinc   

1720 
419 

850-1000 
1020-1030 

900-940 
1100-1250 

1350-1530 
1530 

3128 
786.2 

1562-1832 
1868-1886 

1652-1724 
2012-2282 

2462-2786 
2786 

Bronze 
(90CulOSn) 
Brass 
(90CulOZn) 
Brass 
(70Cu30Zn) 
Cast  Pig  Iron 



Open  Hearth 
Steel 

Wrought  Iron 
Bars    

*  Density  compared  with  air. 


MISCELLANEOUS  NOTES  AND  DATA  253 

MENSURATION  FACTORS 

Diameter  of  a  Circle  X  3. 1416  —  Circumference. 

Radius  of  a  Circle  X  6.2832  —  Circumference. 

Square  of  the  Radius  of  a  Circle  X  3.1416  =  Area. 

Square  of  the  Diameter  of  a  Circle  X  0.7854  =  Area. 

Square  of  the  Circumference  of  a  Circle  X  0.07958  =  Area. 

Half  the  Circumference  of  a  Circle  X  half  its  Diameter  =  Area. 

Doubling  the  Diameter  of  a  Circle  Increases  its  Area  Four  Times. 

Circumference  of  a  Circle  X  0.15915  =  Radius. 

Square  Root  of  the  Area  of  a  Circle  X  0.56419  =  Radius. 

Circumference  of  a  Circle  X  0.31831  =  Diameter. 

Square  Root  of  the  Area  of  a  Circle  X  1.12838  =  Diameter. 

Diameter  of  a  Circle  X  0.8660  =  Side  of  an  Inscribed  Equilateral  Triangle. 

Diameter  of  a  Circle  X  0.7071  —  Side  of  an  Inscribed  Square. 

Circumference  of  a  Circle  X  0.2251  =  Side  of  an  Inscribed  Square. 

Circumference  of  a  Circle  X  0.2821  =  Side  of  an  Equal  Square. 

Diameter  of   a   Circle  X  0.8862  =  Side  of   an  Equal   Square. 

Side  of  a  Square  X  1.1142  =  Diameter  of  Circumscribed  Circle. 

Side  of  a  Square  X  4.443  =  Circumference  of  Circumscribed  Circle. 

Base  of  a  Triangle  X  one-half  the  Altitude  — •  Area. 

Multiplying  both  Diameters  and  0.7854  together  =  Area  of  an  Elipse. 

Surface  of  a  Sphere  X  one-sixth  of  its  Diameter  —  Cubical  Contents. 

Circumference  of  a  Sphere  X  its  Diameter  =  Surface  Area. 

Square  of  the  Diameter  of  a  Sphere  X  3.1416  —  Surface  Area. 

Square  of  the  Circumference  of  a  Sphere  X  0.3183  =  Surface  Area. 

Cube  of  the  Diameter  of  a  Sphere  X  0.5236  =  Cubical  Contents. 

Cube  of  the  Circumference  of  a  Sphere  X  0.016887  =  Cubical  Contents. 

Radius  of  a  Sphere  X  1.1547  =  Side  of  Inscribed  Cube. 

Square  Root  of  one-third  of  the  square  of  the  Diameter  of  a  Sphere  =  Side 
of  Inscribed  Cube. 

Area  of  its  Base  X  one-third  of  its  Altitude  —  Cubical  Contents  of  a, Cone 
of  Pyramid,  whether  Round,  Square  or  Triangular. 

Altitude  of  Trapezoid  X  one-half  the  sum  of  its  Parallel  Sides  =  Area. 

Area  of  a  Rectangle  =  Length  X  Breadth. 

Side  of  a  Square  X  1.128  =  Diameter  of  an  Equal  Circle. 

Side  of  a  Square  X  3.574=  Circumference  of  an  Equal  Circle. 

Square  Inches  X  1.273  =  Circle  Inches  of  an  Equal  Circle. 

ELECTRICAL  UNITS 
(Circular  No.  60,  Bureau  of  Standards') 

OHM — The  international  ohm  (unit  of  resistance)  is  the  resistance  offered 
to  an  unvarying  electric  current  by  a  column  of  mercury  at  the  tempera- 
ture of  melting  ice,  14.4521  grams  in  mass,  of  a  constant  cross-sectional 
area  and  of  a  length  of  106.300  centimeters. 
1  International  ohm  =  1.00052  absolute  ohms. 
1  Absolute  ohm  =0.99948  international  ohm. 
1  Absolute  ohm  =1,000,000,000  c.g.s.  magnetic  units. 

AMPERE — The  international  ampere  (rate  of  flow  of  electricity)  is  the 
unvarying  electric  current  which,  when  passed  through  a  solution  of 
nitrate  of  silver  in  water,  in  accordance  with  the  Specification  II  at- 
tached to  these  resolutions  (1908  International  Conference  on  Electrical 
Units  and  Standards  held  at  London),  deposits  silver  at  the  rate  of 
0.00111800  of  a  gram  per  second.  One  ampere  is  also  equal  to  one 
coulomb  per  second. 

1  International  ampere  =  0.99991  absolute  ampere. 
1  Absolute  ampere  =  1.00009  international  amperes. 
1  Absolute  ampere  =  0.1  c.g.s.  magnetic  unit. 


254  ELECTRIC  ARC   WELDING 

VOLT — The  international  volt  (unit  of  electrical  pressure  of  electromotive 
force)  is  the  electrical  pressure  which,  when  steadily  applied  to  a  con- 
ductor the  resistance  of  which  is  one  international  ohm,  will  produce  a 
current  of  one  international  ampere.  The  Weston  normal  cell  gives 
1.0183  international  volts  at  20  degrees  centigrade.  One  kilovolt  equals 
1000  volts. 

1  International  volt  r=  1.00043  absolute  volts. 

1  Absolute  volt  =0.99957  international  volt. 

1  Absolute  volt  =  100,000,000  c.g.s.  magnetic  units. 

WATT — The  international  watt  (unit  of  power)  is  the  energy  expended 
per  second  by  an  unvarying  electric  current  of  one  international  ampere 
under  an  electric  pressure  of  one  international  volt.  One  watt  is  also 
equal  to  one  joule  per  second.  One  kilowatt  is  equal  to  1000  watts. 

1  International  watt—  1.00034  absolute  watts. 

1  Absolute  watt  =  0.99966  international  watt. 

1  Absolute  watt  =  10,000,000  c.g.s.  magnetic  units. 

Watts  X  .7375  =  foot  pounds  per  second. 

COULOMB — The  unit  of  quantity  is  the  coulomb,  which  is  the  quantity  of 
electricity  transferred  by  a  current  of  one  international  ampere  in  one 
second. 

1  International  coulomb  =  0.99991  absolute  coulomb. 

1  Absolute  coulomb  =  1.00009  international  coulombs. 

1  Absolute  coulomb  =  0.1  c.g.s.  magnetic  unit. 

FARAD — The  unit  of  capacity  is  the  international  farad,  which  is  the 
capacity  of  a  condenser  charged  to  a  potential  of  one  international  volt 
by  one  international  coulomb  of  electricity.  The  unit  generally  used  is 
the  microfarad,  which  is  one-millionth  of  a  farad. 

1  International  farad  =  0.99948  absolute  farad. 

1  Absolute  farad  =  1.00052  international  farads. 

1  Absolute  farad  =  1/1,000,000,000  c.g.s.  magnetic  unit. 

HENRY — The  unit  of  inductance  is  the  international  henry,  which  is  the 
inductance  in  a  circuit  when  the  electromotive  force  induced  in  this  cir- 
cuit is  one  international  volt,  while  the  inducing  current  varies  at  the 
rate  of  one  international  ampere  per  second. 

1  International  henry  =  1.00052  absolute  henrys. 

1  Absolute  henry  =  0.99948  international  henry. 

1  Absolute  henry  =  1,000,000,000  c.g.s.  magnetic  units. 

JOULE — The  unit  of  energy  is  the  international  joule,  which  is  the  work 
done  in  transferring  one  international  coulomb  of  electricity  at  a  pres- 
sure of  one  international  volt. 

1  International  joule  =  1.00034  absolute  joules. 

1  Absolute  joule  =  0.99966  international  joule. 

1  Absolute  joule  =  10,000,000  ergs  or  c.g.s.  magnetic  units. 

Joule  X  .7375  =  foot  pounds. 
HORSE-POWER— One  horse-power  equals  746  watts,  or  550  foot-pounds 

per  second,  or  33,000  foot-pounds  per  minute. 
KILOWATT— One  kilowatt  equals  1000  watts,  or  1.3405  horse-power,  or 

737.27  foot-pounds  per  second,  or  44,236  foot-pounds  per  minute. 
KILOWATT-HOUR— One  kilowatt-hour  equals  1000  watt-hours,  or  1.3405 
horse-power  hours,  or  2,654,200  foot-pounds. 


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APR  10 


A* 


JUN  21  1934 
JUL   16  1934 


KB 

NOV    7    1935 


;7"  29  J936 

DEC    3 

NOV     2h  1937 


APR  17 
DEC  26 


LD  21-50m-l,'33 


YC   19530 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


